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[
{
"text": "[Music]",
"start": 0.56,
"duration": 15.46
},
{
"text": "you",
"start": 13.96,
"duration": 2.06
},
{
"text": "okay welcome back everyone to web",
"start": 17.33,
"duration": 3.63
},
{
"text": "programming with Python and JavaScript",
"start": 19.49,
"duration": 3.449
},
{
"text": "and today we turn our attention to the",
"start": 20.96,
"duration": 3.84
},
{
"text": "second of the main programming languages",
"start": 22.939,
"duration": 3.061
},
{
"text": "that would be looking under this class",
"start": 24.8,
"duration": 3.54
},
{
"text": "in particular JavaScript and to get an",
"start": 26.0,
"duration": 3.57
},
{
"text": "understanding for why it is that",
"start": 28.34,
"duration": 3.269
},
{
"text": "JavaScript is actually helpful let's go",
"start": 29.57,
"duration": 3.9
},
{
"text": "back and revisit this diagram of what",
"start": 31.609,
"duration": 3.541
},
{
"text": "communication over the Internet will",
"start": 33.47,
"duration": 3.45
},
{
"text": "generally look like oftentimes we'll",
"start": 35.15,
"duration": 3.24
},
{
"text": "have a user otherwise known as the",
"start": 36.92,
"duration": 3.69
},
{
"text": "client using their computer on their web",
"start": 38.39,
"duration": 3.87
},
{
"text": "browser whether that's Chrome or Safari",
"start": 40.61,
"duration": 3.99
},
{
"text": "or some other web browser that sends an",
"start": 42.26,
"duration": 5.549
},
{
"text": "HTTP request a web request to some sort",
"start": 44.6,
"duration": 5.459
},
{
"text": "of web server that server then processes",
"start": 47.809,
"duration": 4.5
},
{
"text": "that request and then returns some sort",
"start": 50.059,
"duration": 3.991
},
{
"text": "of response that comes back to the",
"start": 52.309,
"duration": 3.96
},
{
"text": "client thus far all of the code that",
"start": 54.05,
"duration": 4.2
},
{
"text": "we've written the Python web application",
"start": 56.269,
"duration": 4.02
},
{
"text": "code running in a Django web application",
"start": 58.25,
"duration": 4.05
},
{
"text": "for example has all been code that runs",
"start": 60.289,
"duration": 4.291
},
{
"text": "on some sort of server code that is",
"start": 62.3,
"duration": 4.11
},
{
"text": "listening for requests doing some",
"start": 64.58,
"duration": 3.45
},
{
"text": "computation in order to process that",
"start": 66.41,
"duration": 3.69
},
{
"text": "request and then generating some sort of",
"start": 68.03,
"duration": 4.259
},
{
"text": "response usually in the form of an HTML",
"start": 70.1,
"duration": 4.56
},
{
"text": "template that we then send back to the",
"start": 72.289,
"duration": 4.5
},
{
"text": "client what JavaScript is going to",
"start": 74.66,
"duration": 4.14
},
{
"text": "enable us to do is to begin to write",
"start": 76.789,
"duration": 4.591
},
{
"text": "client-side code javascript is going to",
"start": 78.8,
"duration": 4.019
},
{
"text": "allow us to write code that actually",
"start": 81.38,
"duration": 3.81
},
{
"text": "runs and inside of the users web browser",
"start": 82.819,
"duration": 4.591
},
{
"text": "on the client and this can be useful for",
"start": 85.19,
"duration": 3.989
},
{
"text": "a number of reasons one if there's",
"start": 87.41,
"duration": 3.51
},
{
"text": "computation that we want to do but we",
"start": 89.179,
"duration": 3.181
},
{
"text": "don't need to go out and reach out to a",
"start": 90.92,
"duration": 3.449
},
{
"text": "server in order to do so we can do the",
"start": 92.36,
"duration": 4.349
},
{
"text": "computation potentially faster just by",
"start": 94.369,
"duration": 4.051
},
{
"text": "running the code exclusively on the",
"start": 96.709,
"duration": 3.66
},
{
"text": "client and in addition to that we can",
"start": 98.42,
"duration": 3.869
},
{
"text": "begin to make our web pages a whole lot",
"start": 100.369,
"duration": 3.75
},
{
"text": "more interactive javascript is going to",
"start": 102.289,
"duration": 3.631
},
{
"text": "give us the ability to directly",
"start": 104.119,
"duration": 4.021
},
{
"text": "manipulate the Dom where again the Dom",
"start": 105.92,
"duration": 5.009
},
{
"text": "is the document object model that tree",
"start": 108.14,
"duration": 5.069
},
{
"text": "like hierarchy that represents the web",
"start": 110.929,
"duration": 3.78
},
{
"text": "page that the user happens to be looking",
"start": 113.209,
"duration": 3.841
},
{
"text": "at so javascript will enable us to write",
"start": 114.709,
"duration": 4.05
},
{
"text": "code that directly manipulates the",
"start": 117.05,
"duration": 3.42
},
{
"text": "content on the web page and we'll see",
"start": 118.759,
"duration": 3.661
},
{
"text": "how that can be quite powerful very soon",
"start": 120.47,
"duration": 4.709
},
{
"text": "so how do we then use JavaScript inside",
"start": 122.42,
"duration": 5.19
},
{
"text": "of a web page in order to add some code",
"start": 125.179,
"duration": 4.321
},
{
"text": "add some programming logic to a web page",
"start": 127.61,
"duration": 4.739
},
{
"text": "well so far we've already seen HTML the",
"start": 129.5,
"duration": 4.08
},
{
"text": "language we use to describe the",
"start": 132.349,
"duration": 2.28
},
{
"text": "structure of a web page",
"start": 133.58,
"duration": 3.84
},
{
"text": "where a HTML page just describes the",
"start": 134.629,
"duration": 4.351
},
{
"text": "structure of a page and in terms of",
"start": 137.42,
"duration": 3.84
},
{
"text": "nested tags we had those head tags at",
"start": 138.98,
"duration": 4.17
},
{
"text": "the top of the page the body tags that",
"start": 141.26,
"duration": 3.54
},
{
"text": "describe the structure of the page and",
"start": 143.15,
"duration": 2.94
},
{
"text": "then additional tags that could be",
"start": 144.8,
"duration": 3.63
},
{
"text": "nested within those and in order to add",
"start": 146.09,
"duration": 4.29
},
{
"text": "JavaScript to a web page if it's as",
"start": 148.43,
"duration": 2.76
},
{
"text": "simple as include",
"start": 150.38,
"duration": 3.06
},
{
"text": "some script tags that are often located",
"start": 151.19,
"duration": 5.79
},
{
"text": "inside of the HTML page itself when we",
"start": 153.44,
"duration": 5.34
},
{
"text": "use these script tags we're telling the",
"start": 156.98,
"duration": 3.99
},
{
"text": "browser that anything in between these",
"start": 158.78,
"duration": 4.14
},
{
"text": "script tags should be interpreted in",
"start": 160.97,
"duration": 4.41
},
{
"text": "this case as JavaScript code that the",
"start": 162.92,
"duration": 5.37
},
{
"text": "web browser is then going to execute so",
"start": 165.38,
"duration": 4.83
},
{
"text": "our very first program for example might",
"start": 168.29,
"duration": 3.93
},
{
"text": "just look like a line of code inside of",
"start": 170.21,
"duration": 3.69
},
{
"text": "the script tags something like this",
"start": 172.22,
"duration": 4.35
},
{
"text": "where alert for example is the name of a",
"start": 173.9,
"duration": 4.14
},
{
"text": "function a function that's going to",
"start": 176.57,
"duration": 3.99
},
{
"text": "produce an alert and then just as with",
"start": 178.04,
"duration": 4.05
},
{
"text": "functions in Python functions in",
"start": 180.56,
"duration": 3.45
},
{
"text": "JavaScript can take arguments so in",
"start": 182.09,
"duration": 3.69
},
{
"text": "between these parentheses we have an",
"start": 184.01,
"duration": 3.78
},
{
"text": "argument something like a string hello",
"start": 185.78,
"duration": 3.57
},
{
"text": "world the text that we would like to",
"start": 187.79,
"duration": 4.26
},
{
"text": "display to the user so let's go ahead",
"start": 189.35,
"duration": 4.56
},
{
"text": "and give this a try and see how we can",
"start": 192.05,
"duration": 3.57
},
{
"text": "actually use this code to write",
"start": 193.91,
"duration": 3.93
},
{
"text": "JavaScript that is going to run inside",
"start": 195.62,
"duration": 4.56
},
{
"text": "of the user's web browser I'll go ahead",
"start": 197.84,
"duration": 4.44
},
{
"text": "and create a new file that will call",
"start": 200.18,
"duration": 6.23
},
{
"text": "hello HTML and inside of it I'll include",
"start": 202.28,
"duration": 8.01
},
{
"text": "the same basic HTML structure that we've",
"start": 206.41,
"duration": 5.38
},
{
"text": "already seen before where I have a head",
"start": 210.29,
"duration": 3.51
},
{
"text": "section that has a title and then a body",
"start": 211.79,
"duration": 4.61
},
{
"text": "that maybe just says hello for example",
"start": 213.8,
"duration": 5.82
},
{
"text": "and so now what I'd like to do is add a",
"start": 216.4,
"duration": 5.14
},
{
"text": "little bit of JavaScript to this web",
"start": 219.62,
"duration": 4.14
},
{
"text": "page so in the head section of my web",
"start": 221.54,
"duration": 4.8
},
{
"text": "page I'm gonna go ahead and add a script",
"start": 223.76,
"duration": 5.07
},
{
"text": "tag we're in between these script tags",
"start": 226.34,
"duration": 5.22
},
{
"text": "now I can write JavaScript code code",
"start": 228.83,
"duration": 3.6
},
{
"text": "that is going to be written in",
"start": 231.56,
"duration": 2.85
},
{
"text": "JavaScript that will run inside of the",
"start": 232.43,
"duration": 4.38
},
{
"text": "web browser when the user actually opens",
"start": 234.41,
"duration": 4.23
},
{
"text": "up this page and for now I'll just say",
"start": 236.81,
"duration": 6.24
},
{
"text": "alert and then hello world it turns out",
"start": 238.64,
"duration": 6.21
},
{
"text": "in JavaScript you can use either single",
"start": 243.05,
"duration": 3.45
},
{
"text": "quotation marks or double quotation",
"start": 244.85,
"duration": 3.21
},
{
"text": "marks in order to represent strings and",
"start": 246.5,
"duration": 3.48
},
{
"text": "I'll generally use single quotation",
"start": 248.06,
"duration": 4.17
},
{
"text": "marks here just by convention so here",
"start": 249.98,
"duration": 3.479
},
{
"text": "I'm running a function called alert",
"start": 252.23,
"duration": 2.46
},
{
"text": "that's going to display an alert",
"start": 253.459,
"duration": 2.791
},
{
"text": "something like hello world to the user",
"start": 254.69,
"duration": 3.96
},
{
"text": "and that's going to be inside of the",
"start": 256.25,
"duration": 6.69
},
{
"text": "script tags of this HTML page so now if",
"start": 258.65,
"duration": 6.39
},
{
"text": "I want to actually open the page up I",
"start": 262.94,
"duration": 4.32
},
{
"text": "can open hello dot HTML or you could",
"start": 265.04,
"duration": 3.6
},
{
"text": "just visit it inside of your web browser",
"start": 267.26,
"duration": 2.7
},
{
"text": "whether it's Chrome or something else",
"start": 268.64,
"duration": 3.39
},
{
"text": "and now at the top of the page what",
"start": 269.96,
"duration": 3.63
},
{
"text": "you'll notice is that I get a little bit",
"start": 272.03,
"duration": 3.75
},
{
"text": "of an alert some interaction where it",
"start": 273.59,
"duration": 4.35
},
{
"text": "says this page says hello world and",
"start": 275.78,
"duration": 3.48
},
{
"text": "gives me an option to like press a",
"start": 277.94,
"duration": 3.599
},
{
"text": "button for example like Hello I'd like",
"start": 279.26,
"duration": 3.75
},
{
"text": "the OK button that'll say all right",
"start": 281.539,
"duration": 2.851
},
{
"text": "dismiss the alert now",
"start": 283.01,
"duration": 3.09
},
{
"text": "and this is our very first example of",
"start": 284.39,
"duration": 2.94
},
{
"text": "JavaScript we have a function called",
"start": 286.1,
"duration": 3.45
},
{
"text": "alert built into JavaScript for our web",
"start": 287.33,
"duration": 3.96
},
{
"text": "browser and our web browser knows that",
"start": 289.55,
"duration": 3.48
},
{
"text": "when we call the alert function the",
"start": 291.29,
"duration": 3.6
},
{
"text": "browser should display an alert message",
"start": 293.03,
"duration": 3.72
},
{
"text": "that looks a little something like that",
"start": 294.89,
"duration": 3.75
},
{
"text": "and if i click the ok' button to dismiss",
"start": 296.75,
"duration": 3.9
},
{
"text": "the alert then we go ahead and get back",
"start": 298.64,
"duration": 4.41
},
{
"text": "the original page that i had from the",
"start": 300.65,
"duration": 5.4
},
{
"text": "beginning and so now we can begin to",
"start": 303.05,
"duration": 4.98
},
{
"text": "imagine that using this ability to",
"start": 306.05,
"duration": 4.11
},
{
"text": "programmatically display alerts that we",
"start": 308.03,
"duration": 4.11
},
{
"text": "can add additional features to our",
"start": 310.16,
"duration": 4.17
},
{
"text": "applications as well and one big area",
"start": 312.14,
"duration": 3.57
},
{
"text": "where javascript can be quite powerful",
"start": 314.33,
"duration": 3.81
},
{
"text": "is with isn't driven programming and",
"start": 315.71,
"duration": 3.96
},
{
"text": "what event-driven programming is all",
"start": 318.14,
"duration": 3.45
},
{
"text": "about is thinking about things that",
"start": 319.67,
"duration": 4.14
},
{
"text": "happen on the web in terms of events",
"start": 321.59,
"duration": 4.29
},
{
"text": "that happen what are some examples of",
"start": 323.81,
"duration": 4.08
},
{
"text": "events events are things like the user",
"start": 325.88,
"duration": 4.38
},
{
"text": "clicks on a button or the user selects",
"start": 327.89,
"duration": 4.02
},
{
"text": "something from a drop-down list or the",
"start": 330.26,
"duration": 3.6
},
{
"text": "user Scrolls through a list or submits a",
"start": 331.91,
"duration": 3.78
},
{
"text": "form anything the user does and can",
"start": 333.86,
"duration": 3.54
},
{
"text": "generally be thought of as an event and",
"start": 335.69,
"duration": 4.05
},
{
"text": "what we can do with javascript is add",
"start": 337.4,
"duration": 4.98
},
{
"text": "event listeners or event handlers things",
"start": 339.74,
"duration": 5.1
},
{
"text": "that say when an event happens go ahead",
"start": 342.38,
"duration": 4.74
},
{
"text": "and run this particular block of code or",
"start": 344.84,
"duration": 4.74
},
{
"text": "this function for example and using that",
"start": 347.12,
"duration": 4.26
},
{
"text": "we can begin to allow our JavaScript",
"start": 349.58,
"duration": 4.05
},
{
"text": "code to respond to how the user is",
"start": 351.38,
"duration": 4.29
},
{
"text": "actually interacting with our web page",
"start": 353.63,
"duration": 3.72
},
{
"text": "to say when the user clicks on a button",
"start": 355.67,
"duration": 3.56
},
{
"text": "I would like to run this particular",
"start": 357.35,
"duration": 5.4
},
{
"text": "JavaScript function for example so let's",
"start": 359.23,
"duration": 5.29
},
{
"text": "go ahead and give that a try I'll go",
"start": 362.75,
"duration": 3.99
},
{
"text": "ahead and now instead of just saying",
"start": 364.52,
"duration": 4.86
},
{
"text": "alert hello world let me put this alert",
"start": 366.74,
"duration": 4.74
},
{
"text": "inside of a function and to create a",
"start": 369.38,
"duration": 4.17
},
{
"text": "function in JavaScript you just use the",
"start": 371.48,
"duration": 4.41
},
{
"text": "keyword function followed by the name of",
"start": 373.55,
"duration": 3.54
},
{
"text": "the function I'll call the function",
"start": 375.89,
"duration": 3.03
},
{
"text": "hello for example and then in",
"start": 377.09,
"duration": 3.84
},
{
"text": "parenthesis any inputs that function",
"start": 378.92,
"duration": 3.75
},
{
"text": "takes this hello function is not going",
"start": 380.93,
"duration": 3.18
},
{
"text": "to take any input so I'll just use an",
"start": 382.67,
"duration": 4.53
},
{
"text": "empty set of parentheses and then inside",
"start": 384.11,
"duration": 5.82
},
{
"text": "of curly braces I include any of the",
"start": 387.2,
"duration": 5.04
},
{
"text": "code that I want to run in this function",
"start": 389.93,
"duration": 5.01
},
{
"text": "and so what I've done here now is create",
"start": 392.24,
"duration": 5.1
},
{
"text": "a function called hello and then inside",
"start": 394.94,
"duration": 3.87
},
{
"text": "of the curly braces have defined the",
"start": 397.34,
"duration": 3.06
},
{
"text": "body of the function what code should",
"start": 398.81,
"duration": 3.93
},
{
"text": "run when I run the hello function and",
"start": 400.4,
"duration": 4.71
},
{
"text": "what the hello function should do is it",
"start": 402.74,
"duration": 3.96
},
{
"text": "should display an alert that in this",
"start": 405.11,
"duration": 4.59
},
{
"text": "case says a hello world so now what I'd",
"start": 406.7,
"duration": 5.88
},
{
"text": "like to do is get this function to run",
"start": 409.7,
"duration": 5.46
},
{
"text": "when something happens on the page for",
"start": 412.58,
"duration": 5.37
},
{
"text": "example when a user clicks on a button",
"start": 415.16,
"duration": 4.08
},
{
"text": "so to do that the first thing I'll need",
"start": 417.95,
"duration": 3.69
},
{
"text": "to do is actually create a button so add",
"start": 419.24,
"duration": 4.56
},
{
"text": "a button that just says like click here",
"start": 421.64,
"duration": 5.82
},
{
"text": "for example so now if i refresh this",
"start": 423.8,
"duration": 7.44
},
{
"text": "page i now see that i have hello and I",
"start": 427.46,
"duration": 5.01
},
{
"text": "also have this button that says click",
"start": 431.24,
"duration": 3.69
},
{
"text": "here but when I click here like nothing",
"start": 432.47,
"duration": 3.69
},
{
"text": "happens I'm clicking the click here",
"start": 434.93,
"duration": 2.46
},
{
"text": "button but it's not changing anything",
"start": 436.16,
"duration": 3.24
},
{
"text": "because I haven't yet said what should",
"start": 437.39,
"duration": 4.56
},
{
"text": "happen when the user does click on this",
"start": 439.4,
"duration": 4.71
},
{
"text": "button and so one way we could do this",
"start": 441.95,
"duration": 5.1
},
{
"text": "is by adding an attribute to this HTML",
"start": 444.11,
"duration": 6.66
},
{
"text": "element called unclick what this is",
"start": 447.05,
"duration": 5.97
},
{
"text": "going to do is it's going to add an on",
"start": 450.77,
"duration": 3.99
},
{
"text": "click handler to this button it's going",
"start": 453.02,
"duration": 3.48
},
{
"text": "to say what should happen when the user",
"start": 454.76,
"duration": 3.96
},
{
"text": "clicks on this button and I'm going to",
"start": 456.5,
"duration": 4.19
},
{
"text": "set the onclick attribute equal to",
"start": 458.72,
"duration": 5.13
},
{
"text": "running the function hello and in order",
"start": 460.69,
"duration": 4.84
},
{
"text": "to run a function in JavaScript just as",
"start": 463.85,
"duration": 3.42
},
{
"text": "you ran a function with Python you use",
"start": 465.53,
"duration": 3.81
},
{
"text": "the name of the function followed by a",
"start": 467.27,
"duration": 3.81
},
{
"text": "set of parentheses to say go ahead and",
"start": 469.34,
"duration": 3.75
},
{
"text": "actually run this function using this",
"start": 471.08,
"duration": 3.93
},
{
"text": "parenthesis calls the function another",
"start": 473.09,
"duration": 3.54
},
{
"text": "word for running the function and the",
"start": 475.01,
"duration": 2.97
},
{
"text": "fact that there's nothing in between the",
"start": 476.63,
"duration": 2.82
},
{
"text": "parentheses means we're not providing",
"start": 477.98,
"duration": 3.63
},
{
"text": "anything as input to the hello function",
"start": 479.45,
"duration": 3.72
},
{
"text": "though if the hello function did take",
"start": 481.61,
"duration": 3.6
},
{
"text": "inputs we could certainly add that in",
"start": 483.17,
"duration": 5.46
},
{
"text": "between the parentheses so now I've tied",
"start": 485.21,
"duration": 5.31
},
{
"text": "the two pieces of this page together I",
"start": 488.63,
"duration": 3.69
},
{
"text": "have a button that says click here and",
"start": 490.52,
"duration": 4.62
},
{
"text": "I've added an onclick handler that says",
"start": 492.32,
"duration": 4.26
},
{
"text": "that when you click on the button you",
"start": 495.14,
"duration": 4.05
},
{
"text": "should run the hello function and then",
"start": 496.58,
"duration": 4.14
},
{
"text": "up above I've defined the hello function",
"start": 499.19,
"duration": 3.54
},
{
"text": "to say what should the hello function do",
"start": 500.72,
"duration": 3.93
},
{
"text": "well when the function is called we're",
"start": 502.73,
"duration": 3.57
},
{
"text": "going to display an alert that in this",
"start": 504.65,
"duration": 4.56
},
{
"text": "case says hello world so now we should",
"start": 506.3,
"duration": 6.63
},
{
"text": "be able to refresh the page we still see",
"start": 509.21,
"duration": 5.22
},
{
"text": "the same thing at least initially where",
"start": 512.93,
"duration": 2.85
},
{
"text": "it just says hello and a button that",
"start": 514.43,
"duration": 4.2
},
{
"text": "tells me to click here but now if I go",
"start": 515.78,
"duration": 3.93
},
{
"text": "ahead and click the button that says",
"start": 518.63,
"duration": 3.57
},
{
"text": "click here well then I get the alert",
"start": 519.71,
"duration": 4.74
},
{
"text": "that says this page says hello world I",
"start": 522.2,
"duration": 4.38
},
{
"text": "can press ok and this event handler is",
"start": 524.45,
"duration": 3.36
},
{
"text": "always going to work I click the button",
"start": 526.58,
"duration": 3.24
},
{
"text": "again and I get the alert a second time",
"start": 527.81,
"duration": 3.24
},
{
"text": "because every time I click the button",
"start": 529.82,
"duration": 2.94
},
{
"text": "it's going to call the hello function",
"start": 531.05,
"duration": 3.66
},
{
"text": "again and when I click the hello when",
"start": 532.76,
"duration": 3.69
},
{
"text": "the hello function runs and it is going",
"start": 534.71,
"duration": 5.4
},
{
"text": "to display this particular alert so this",
"start": 536.45,
"duration": 5.85
},
{
"text": "now appears to give us a fair amount of",
"start": 540.11,
"duration": 4.68
},
{
"text": "power and much as in other programming",
"start": 542.3,
"duration": 4.35
},
{
"text": "languages languages like Python or other",
"start": 544.79,
"duration": 3.03
},
{
"text": "languages you might have worked with",
"start": 546.65,
"duration": 3.39
},
{
"text": "JavaScript has all these same types of",
"start": 547.82,
"duration": 3.8
},
{
"text": "language features so far",
"start": 550.04,
"duration": 3.41
},
{
"text": "we've seen datatypes things like a",
"start": 551.62,
"duration": 3.51
},
{
"text": "string but we also have other data types",
"start": 553.45,
"duration": 3.33
},
{
"text": "that we'll take a look at soon too we've",
"start": 555.13,
"duration": 3.48
},
{
"text": "seen functions some functions that are",
"start": 556.78,
"duration": 3.6
},
{
"text": "built into JavaScript like the alert",
"start": 558.61,
"duration": 3.66
},
{
"text": "function and other functions that we can",
"start": 560.38,
"duration": 3.51
},
{
"text": "write for ourselves functions like hello",
"start": 562.27,
"duration": 3.63
},
{
"text": "but we also have the ability to include",
"start": 563.89,
"duration": 4.83
},
{
"text": "things like variables inside of our",
"start": 565.9,
"duration": 5.1
},
{
"text": "program as well so what might that look",
"start": 568.72,
"duration": 2.61
},
{
"text": "like",
"start": 571.0,
"duration": 2.31
},
{
"text": "well I'll go ahead and create a new file",
"start": 571.33,
"duration": 5.82
},
{
"text": "it will call counter HTML and counter is",
"start": 573.31,
"duration": 5.4
},
{
"text": "going to have some of the similar code",
"start": 577.15,
"duration": 2.79
},
{
"text": "to hello so I'll just go ahead and copy",
"start": 578.71,
"duration": 3.27
},
{
"text": "it for now but I'll clear out the script",
"start": 579.94,
"duration": 4.02
},
{
"text": "section change the title from hello to",
"start": 581.98,
"duration": 6.51
},
{
"text": "counter and now inside I'll get rid of",
"start": 583.96,
"duration": 6.03
},
{
"text": "the button or actually I'll keep the",
"start": 588.49,
"duration": 3.69
},
{
"text": "button but instead of saying click here",
"start": 589.99,
"duration": 5.19
},
{
"text": "the button is going to say count I'd",
"start": 592.18,
"duration": 4.14
},
{
"text": "like to create a program that just",
"start": 595.18,
"duration": 3.12
},
{
"text": "counts for me from zero to one two two",
"start": 596.32,
"duration": 5.76
},
{
"text": "three four so on and so forth and now in",
"start": 598.3,
"duration": 6.0
},
{
"text": "order to do that in order to have some",
"start": 602.08,
"duration": 4.23
},
{
"text": "way of counting repeatedly zero one two",
"start": 604.3,
"duration": 4.68
},
{
"text": "three four five I'm going to need a have",
"start": 606.31,
"duration": 4.38
},
{
"text": "some sort of variable inside of my",
"start": 608.98,
"duration": 3.21
},
{
"text": "program something that is keeping track",
"start": 610.69,
"duration": 3.69
},
{
"text": "of data like the number that I'm",
"start": 612.19,
"duration": 4.35
},
{
"text": "currently have counted to so in order to",
"start": 614.38,
"duration": 3.87
},
{
"text": "do that in JavaScript I can say",
"start": 616.54,
"duration": 5.07
},
{
"text": "something like let counter equal zero",
"start": 618.25,
"duration": 5.76
},
{
"text": "this is the way in JavaScript that I",
"start": 621.61,
"duration": 5.07
},
{
"text": "define a new variable I first say let",
"start": 624.01,
"duration": 4.68
},
{
"text": "counter meaning let there be a new",
"start": 626.68,
"duration": 4.14
},
{
"text": "variable called counter and I'm going to",
"start": 628.69,
"duration": 4.17
},
{
"text": "initially set the value of counter equal",
"start": 630.82,
"duration": 5.01
},
{
"text": "to the number zero and now when I click",
"start": 632.86,
"duration": 4.65
},
{
"text": "on the button instead of running the",
"start": 635.83,
"duration": 3.72
},
{
"text": "hello function I'm going to go ahead and",
"start": 637.51,
"duration": 4.95
},
{
"text": "run the count function which doesn't",
"start": 639.55,
"duration": 4.95
},
{
"text": "exist yet but I'll now write it I'll",
"start": 642.46,
"duration": 5.43
},
{
"text": "define a function called count and what",
"start": 644.5,
"duration": 6.06
},
{
"text": "the count function is going to do is it",
"start": 647.89,
"duration": 5.28
},
{
"text": "is going to first increment the value of",
"start": 650.56,
"duration": 4.26
},
{
"text": "counter and a number of ways I could do",
"start": 653.17,
"duration": 3.36
},
{
"text": "that one is my saying counter equals",
"start": 654.82,
"duration": 4.98
},
{
"text": "counter plus one to say go ahead and",
"start": 656.53,
"duration": 4.53
},
{
"text": "reset the value of counter to whatever",
"start": 659.8,
"duration": 3.48
},
{
"text": "it counter is plus one and there are a",
"start": 661.06,
"duration": 3.78
},
{
"text": "couple of shorthand notations for this I",
"start": 663.28,
"duration": 3.72
},
{
"text": "could equivalently say counter plus",
"start": 664.84,
"duration": 4.38
},
{
"text": "equals one to say add one to the counter",
"start": 667.0,
"duration": 5.04
},
{
"text": "or in the case of adding one javascript",
"start": 669.22,
"duration": 4.2
},
{
"text": "much like languages like c if you've",
"start": 672.04,
"duration": 3.09
},
{
"text": "seen them before and support notation",
"start": 673.42,
"duration": 4.02
},
{
"text": "like this counter plus plus which just",
"start": 675.13,
"duration": 3.75
},
{
"text": "means take the value of counter and",
"start": 677.44,
"duration": 2.88
},
{
"text": "increment it add 1 to it",
"start": 678.88,
"duration": 3.78
},
{
"text": "so I'll add 1 to the value of counter",
"start": 680.32,
"duration": 4.98
},
{
"text": "and then I'll just display an alert",
"start": 682.66,
"duration": 5.46
},
{
"text": "that has whatever the current value of",
"start": 685.3,
"duration": 6.06
},
{
"text": "counter happens to be and so I've",
"start": 688.12,
"duration": 4.77
},
{
"text": "incremented the value of counter and",
"start": 691.36,
"duration": 3.75
},
{
"text": "then displayed an alert that shows me",
"start": 692.89,
"duration": 4.199
},
{
"text": "what's contained inside of counter and",
"start": 695.11,
"duration": 6.419
},
{
"text": "so now if I go ahead and not go to hello",
"start": 697.089,
"duration": 6.661
},
{
"text": "dot HTML but to counter dot HTML instead",
"start": 701.529,
"duration": 5.31
},
{
"text": "I now see that I still see a button that",
"start": 703.75,
"duration": 4.829
},
{
"text": "says count and if I click on that button",
"start": 706.839,
"duration": 4.351
},
{
"text": "I get an alert that this time says one",
"start": 708.579,
"duration": 4.38
},
{
"text": "we've incrementing the value of counter",
"start": 711.19,
"duration": 3.99
},
{
"text": "from zero to one the alert now says 1",
"start": 712.959,
"duration": 4.62
},
{
"text": "and I can press ok if I press count",
"start": 715.18,
"duration": 5.61
},
{
"text": "again the count now goes to 2 I press ok",
"start": 717.579,
"duration": 5.581
},
{
"text": "press count again it goes to 3 and every",
"start": 720.79,
"duration": 3.87
},
{
"text": "time I click count it is going to",
"start": 723.16,
"duration": 3.72
},
{
"text": "increment the value of the variable",
"start": 724.66,
"duration": 4.619
},
{
"text": "counter inside of my JavaScript webpage",
"start": 726.88,
"duration": 4.26
},
{
"text": "and then it's going to display an alert",
"start": 729.279,
"duration": 4.261
},
{
"text": "that is going to contain the value of",
"start": 731.14,
"duration": 3.21
},
{
"text": "that variable",
"start": 733.54,
"duration": 3.03
},
{
"text": "so using alerts now we're able to",
"start": 734.35,
"duration": 3.66
},
{
"text": "manipulate that we can inside a",
"start": 736.57,
"duration": 2.82
},
{
"text": "functions manipulate the values of",
"start": 738.01,
"duration": 3.24
},
{
"text": "variables and then display alerts that",
"start": 739.39,
"duration": 3.9
},
{
"text": "show the contents of those variable ism",
"start": 741.25,
"duration": 3.779
},
{
"text": "but ultimately when users are",
"start": 743.29,
"duration": 3.57
},
{
"text": "interacting with the page it's going to",
"start": 745.029,
"duration": 3.661
},
{
"text": "be fairly annoying if the only way that",
"start": 746.86,
"duration": 4.289
},
{
"text": "we have to interact with the user is via",
"start": 748.69,
"duration": 4.17
},
{
"text": "displaying these alerts the equivalent",
"start": 751.149,
"duration": 3.151
},
{
"text": "of like printing something out except",
"start": 752.86,
"duration": 2.969
},
{
"text": "instead of printing it to a terminal",
"start": 754.3,
"duration": 3.51
},
{
"text": "we're printing it via an alert that",
"start": 755.829,
"duration": 3.901
},
{
"text": "appears on the screen what would be more",
"start": 757.81,
"duration": 3.57
},
{
"text": "interesting and more powerful and much",
"start": 759.73,
"duration": 3.21
},
{
"text": "more useful in the context of a webpage",
"start": 761.38,
"duration": 4.5
},
{
"text": "is if we could programmatically update",
"start": 762.94,
"duration": 4.889
},
{
"text": "the website change something about the",
"start": 765.88,
"duration": 3.57
},
{
"text": "webpage the user is actually seeing",
"start": 767.829,
"duration": 4.111
},
{
"text": "changing the content that happens to be",
"start": 769.45,
"duration": 4.71
},
{
"text": "on the page and turns out Java Script is",
"start": 771.94,
"duration": 3.69
},
{
"text": "going to enable us to do that as well",
"start": 774.16,
"duration": 3.419
},
{
"text": "because Java Script allows us to",
"start": 775.63,
"duration": 4.23
},
{
"text": "manipulate the Dom the document object",
"start": 777.579,
"duration": 4.231
},
{
"text": "model that represents all of the",
"start": 779.86,
"duration": 4.28
},
{
"text": "elements that happen to be on that page",
"start": 781.81,
"duration": 5.339
},
{
"text": "so to do that let's go ahead and return",
"start": 784.14,
"duration": 6.91
},
{
"text": "to hello HTML this again was this paté",
"start": 787.149,
"duration": 6.031
},
{
"text": "web page that just said hello and gave",
"start": 791.05,
"duration": 3.69
},
{
"text": "me a button where if I clicked on that",
"start": 793.18,
"duration": 3.779
},
{
"text": "button it would display an alert that",
"start": 794.74,
"duration": 4.98
},
{
"text": "said hello world now what I'd like to do",
"start": 796.959,
"duration": 5.391
},
{
"text": "is instead of having the hello function",
"start": 799.72,
"duration": 5.309
},
{
"text": "display an alert I'd like to have it",
"start": 802.35,
"duration": 4.989
},
{
"text": "manipulate something on the page and",
"start": 805.029,
"duration": 4.291
},
{
"text": "what might I want me to manipulate well",
"start": 807.339,
"duration": 4.081
},
{
"text": "inside the body of the page I here have",
"start": 809.32,
"duration": 3.9
},
{
"text": "this heading this heading that just says",
"start": 811.42,
"duration": 4.26
},
{
"text": "hello for example which is inside of an",
"start": 813.22,
"duration": 4.65
},
{
"text": "h1 element and what I might like to do",
"start": 815.68,
"duration": 3.63
},
{
"text": "is actually change",
"start": 817.87,
"duration": 4.5
},
{
"text": "that element how can I do that well it",
"start": 819.31,
"duration": 4.86
},
{
"text": "turns out that in JavaScript we have",
"start": 822.37,
"duration": 4.71
},
{
"text": "access to a function called document dot",
"start": 824.17,
"duration": 6.42
},
{
"text": "query selector and what document query",
"start": 827.08,
"duration": 5.46
},
{
"text": "selector is going to do is it is going",
"start": 830.59,
"duration": 4.11
},
{
"text": "to give us the ability to look through",
"start": 832.54,
"duration": 5.37
},
{
"text": "an HTML page and extract an element out",
"start": 834.7,
"duration": 4.92
},
{
"text": "of that page so that we can manipulate",
"start": 837.91,
"duration": 4.95
},
{
"text": "that HTML element using JavaScript code",
"start": 839.62,
"duration": 5.88
},
{
"text": "and so if I want to select like an h1",
"start": 842.86,
"duration": 4.979
},
{
"text": "element I can say document query",
"start": 845.5,
"duration": 4.5
},
{
"text": "selector and then as the argument the",
"start": 847.839,
"duration": 3.901
},
{
"text": "input to document our query selector",
"start": 850.0,
"duration": 4.68
},
{
"text": "I'll go ahead and say each one meaning",
"start": 851.74,
"duration": 5.94
},
{
"text": "go through the page find me an h1",
"start": 854.68,
"duration": 4.62
},
{
"text": "element and query selector is only going",
"start": 857.68,
"duration": 3.0
},
{
"text": "to return one element so if they're",
"start": 859.3,
"duration": 2.61
},
{
"text": "multiple it's going to return the first",
"start": 860.68,
"duration": 3.33
},
{
"text": "thing it finds but here we only have one",
"start": 861.91,
"duration": 4.11
},
{
"text": "h1 element so it's ok I'm gonna say look",
"start": 864.01,
"duration": 4.8
},
{
"text": "through this document try and find in h1",
"start": 866.02,
"duration": 5.13
},
{
"text": "element and when you do I'd like to",
"start": 868.81,
"duration": 4.08
},
{
"text": "manipulate it and the way I'd like to",
"start": 871.15,
"duration": 5.64
},
{
"text": "manipulate it is by saying dot innerhtml",
"start": 872.89,
"duration": 8.36
},
{
"text": "equals of let's say goodbye for example",
"start": 876.79,
"duration": 7.41
},
{
"text": "so alright what's going on here well",
"start": 881.25,
"duration": 4.75
},
{
"text": "right now initially when we first load",
"start": 884.2,
"duration": 3.99
},
{
"text": "the page we have an h1 a big heading at",
"start": 886.0,
"duration": 4.53
},
{
"text": "the top that just says hello and now",
"start": 888.19,
"duration": 4.29
},
{
"text": "when this hello function is called which",
"start": 890.53,
"duration": 3.54
},
{
"text": "is called when this button is clicked on",
"start": 892.48,
"duration": 3.12
},
{
"text": "because it has an on-click attribute",
"start": 894.07,
"duration": 3.93
},
{
"text": "that is equal to hello calling the hello",
"start": 895.6,
"duration": 4.41
},
{
"text": "function what the hello function is",
"start": 898.0,
"duration": 3.6
},
{
"text": "going to do is it's going to say",
"start": 900.01,
"duration": 4.829
},
{
"text": "document query selector h1 find me the",
"start": 901.6,
"duration": 6.78
},
{
"text": "h1 element that will return this element",
"start": 904.839,
"duration": 5.671
},
{
"text": "right here a JavaScript representation",
"start": 908.38,
"duration": 4.77
},
{
"text": "of this HTML element that is just an h1",
"start": 910.51,
"duration": 5.85
},
{
"text": "whose HTML inside of it says hello and",
"start": 913.15,
"duration": 6.24
},
{
"text": "if I want to change that HTML I can do",
"start": 916.36,
"duration": 5.24
},
{
"text": "that by modifying the inner HTML",
"start": 919.39,
"duration": 5.64
},
{
"text": "property of the JavaScript elephant in",
"start": 921.6,
"duration": 5.29
},
{
"text": "order to update a property of anything",
"start": 925.03,
"duration": 3.72
},
{
"text": "in JavaScript will generally use this",
"start": 926.89,
"duration": 4.02
},
{
"text": "dot notation we're dot accesses of",
"start": 928.75,
"duration": 4.56
},
{
"text": "property of some particular object and",
"start": 930.91,
"duration": 4.619
},
{
"text": "so I have this element this h1 and",
"start": 933.31,
"duration": 5.04
},
{
"text": "saying dot inner HTML means take that",
"start": 935.529,
"duration": 4.741
},
{
"text": "element and access its inner HTML",
"start": 938.35,
"duration": 4.05
},
{
"text": "property some property of that object",
"start": 940.27,
"duration": 4.259
},
{
"text": "and I would like to update its inner",
"start": 942.4,
"duration": 4.83
},
{
"text": "HTML to just in this case be the word",
"start": 944.529,
"duration": 4.741
},
{
"text": "goodbye followed by an exclamation point",
"start": 947.23,
"duration": 3.32
},
{
"text": "for example",
"start": 949.27,
"duration": 3.8
},
{
"text": "so now what we'll see is that when we",
"start": 950.55,
"duration": 4.95
},
{
"text": "run this page when we open this page up",
"start": 953.07,
"duration": 6.36
},
{
"text": "as by opening up hello HTML I still see",
"start": 955.5,
"duration": 5.73
},
{
"text": "an h1 that says hello I still see a",
"start": 959.43,
"duration": 4.86
},
{
"text": "button that says click here but now when",
"start": 961.23,
"duration": 4.62
},
{
"text": "I actually click on the button click",
"start": 964.29,
"duration": 4.229
},
{
"text": "here you'll see that hello changes to",
"start": 965.85,
"duration": 3.179
},
{
"text": "goodbye",
"start": 968.519,
"duration": 3.031
},
{
"text": "we've run JavaScript code that finds an",
"start": 969.029,
"duration": 4.56
},
{
"text": "h1 element on the page and manipulates",
"start": 971.55,
"duration": 4.32
},
{
"text": "it changing it to something else than it",
"start": 973.589,
"duration": 4.411
},
{
"text": "was originally now every time I click",
"start": 975.87,
"duration": 4.68
},
{
"text": "here nothing else happens because every",
"start": 978.0,
"duration": 4.35
},
{
"text": "time I click here it's going to find the",
"start": 980.55,
"duration": 3.96
},
{
"text": "same h1 and it's going to update its",
"start": 982.35,
"duration": 5.07
},
{
"text": "HTML changing it from hello to goodbye",
"start": 984.51,
"duration": 5.16
},
{
"text": "so maybe what I'd really like then is",
"start": 987.42,
"duration": 4.77
},
{
"text": "the ability to toggle back and forth to",
"start": 989.67,
"duration": 4.349
},
{
"text": "toggle back and forth between hello and",
"start": 992.19,
"duration": 3.209
},
{
"text": "goodbye rather than just change it from",
"start": 994.019,
"duration": 3.661
},
{
"text": "one thing to something else every time I",
"start": 995.399,
"duration": 3.331
},
{
"text": "click the button I'd like it to",
"start": 997.68,
"duration": 3.3
},
{
"text": "alternate back and forth and there are a",
"start": 998.73,
"duration": 3.479
},
{
"text": "number of ways you can imagine doing",
"start": 1000.98,
"duration": 3.299
},
{
"text": "this but one way is by taking advantage",
"start": 1002.209,
"duration": 4.081
},
{
"text": "of conditions so much in the same way",
"start": 1004.279,
"duration": 3.541
},
{
"text": "that a language like Python has",
"start": 1006.29,
"duration": 3.83
},
{
"text": "conditions ifs and LS and else's",
"start": 1007.82,
"duration": 5.34
},
{
"text": "JavaScript too has if and else if and",
"start": 1010.12,
"duration": 5.339
},
{
"text": "else that allow us to describe",
"start": 1013.16,
"duration": 4.83
},
{
"text": "conditions such that we can only run",
"start": 1015.459,
"duration": 4.721
},
{
"text": "certain blocks of code when a particular",
"start": 1017.99,
"duration": 4.67
},
{
"text": "boolean expression is true for example",
"start": 1020.18,
"duration": 5.07
},
{
"text": "so what would that look like well let's",
"start": 1022.66,
"duration": 4.63
},
{
"text": "go ahead and say inside of this hello",
"start": 1025.25,
"duration": 5.78
},
{
"text": "function I can ask a question if",
"start": 1027.29,
"duration": 7.86
},
{
"text": "document query selector H ones inner",
"start": 1031.03,
"duration": 11.62
},
{
"text": "HTML is equal to hello well then go",
"start": 1035.15,
"duration": 11.33
},
{
"text": "ahead and set it to goodbye and else",
"start": 1042.65,
"duration": 6.54
},
{
"text": "then go ahead and update the inner HTML",
"start": 1046.48,
"duration": 6.09
},
{
"text": "this h1 element go ahead and set it to",
"start": 1049.19,
"duration": 7.35
},
{
"text": "hello instead so what is this hello",
"start": 1052.57,
"duration": 5.32
},
{
"text": "function doing it's now a little bit",
"start": 1056.54,
"duration": 2.22
},
{
"text": "more sophisticated",
"start": 1057.89,
"duration": 2.97
},
{
"text": "it now has a condition where I say if",
"start": 1058.76,
"duration": 4.14
},
{
"text": "the keyword if followed by in",
"start": 1060.86,
"duration": 4.199
},
{
"text": "parentheses the condition that I want to",
"start": 1062.9,
"duration": 3.6
},
{
"text": "check for the thing I want to see is",
"start": 1065.059,
"duration": 3.511
},
{
"text": "this true or not and what I'm checking",
"start": 1066.5,
"duration": 5.309
},
{
"text": "for is is let me run document out query",
"start": 1068.57,
"duration": 5.58
},
{
"text": "selector h1 which again looks through",
"start": 1071.809,
"duration": 5.131
},
{
"text": "the page finds me the h1 tag and get to",
"start": 1074.15,
"duration": 4.89
},
{
"text": "that element for me if I look at that",
"start": 1076.94,
"duration": 5.52
},
{
"text": "inner HTML if it is equal to hello then",
"start": 1079.04,
"duration": 5.31
},
{
"text": "I want to do something and this triple",
"start": 1082.46,
"duration": 2.52
},
{
"text": "equals sign",
"start": 1084.35,
"duration": 2.52
},
{
"text": "is JavaScript's way of checking for",
"start": 1084.98,
"duration": 3.6
},
{
"text": "strict equality checking to make sure",
"start": 1086.87,
"duration": 4.23
},
{
"text": "the two values are equal and also that",
"start": 1088.58,
"duration": 4.29
},
{
"text": "their types are the same thing that if",
"start": 1091.1,
"duration": 3.72
},
{
"text": "this is a string this must also be a",
"start": 1092.87,
"duration": 3.78
},
{
"text": "string it turns out in JavaScript is",
"start": 1094.82,
"duration": 3.45
},
{
"text": "also a weaker way to check for equality",
"start": 1096.65,
"duration": 4.62
},
{
"text": "that just uses two equal signs and that",
"start": 1098.27,
"duration": 5.25
},
{
"text": "is going to check the values are the",
"start": 1101.27,
"duration": 4.17
},
{
"text": "same but it's going to allow for a bit",
"start": 1103.52,
"duration": 4.41
},
{
"text": "of differences in type the two things",
"start": 1105.44,
"duration": 4.11
},
{
"text": "might have different types but so long",
"start": 1107.93,
"duration": 3.45
},
{
"text": "as they're basically the same value the",
"start": 1109.55,
"duration": 3.36
},
{
"text": "double equal sign might generally come",
"start": 1111.38,
"duration": 4.23
},
{
"text": "to be true usually if you can you'll",
"start": 1112.91,
"duration": 4.53
},
{
"text": "want to use this triple equal sign the",
"start": 1115.61,
"duration": 3.75
},
{
"text": "strict equality to make sure that not",
"start": 1117.44,
"duration": 3.21
},
{
"text": "only are the types the same but the",
"start": 1119.36,
"duration": 3.12
},
{
"text": "values are the same too and the triple",
"start": 1120.65,
"duration": 3.06
},
{
"text": "equal sign will check both of those",
"start": 1122.48,
"duration": 4.38
},
{
"text": "things so if I go ahead and find the h1",
"start": 1123.71,
"duration": 5.4
},
{
"text": "element and its inner HTML is the word",
"start": 1126.86,
"duration": 5.25
},
{
"text": "hello well then go ahead and find the h1",
"start": 1129.11,
"duration": 4.79
},
{
"text": "element and update its inner HTML",
"start": 1132.11,
"duration": 4.95
},
{
"text": "setting it equal to goodbye for example",
"start": 1133.9,
"duration": 6.64
},
{
"text": "and else go ahead and find that same h1",
"start": 1137.06,
"duration": 6.06
},
{
"text": "element updated inner HTML set it equal",
"start": 1140.54,
"duration": 5.19
},
{
"text": "to hello and again just as in functions",
"start": 1143.12,
"duration": 4.14
},
{
"text": "where we use these curly braces to",
"start": 1145.73,
"duration": 3.69
},
{
"text": "enclose the body of the function all of",
"start": 1147.26,
"duration": 3.78
},
{
"text": "the lines of code that are inside of the",
"start": 1149.42,
"duration": 3.6
},
{
"text": "function JavaScript does the same thing",
"start": 1151.04,
"duration": 3.96
},
{
"text": "to that inside of a condition when we",
"start": 1153.02,
"duration": 3.93
},
{
"text": "want to express that this is inside the",
"start": 1155.0,
"duration": 4.17
},
{
"text": "body of an if condition I can use curly",
"start": 1156.95,
"duration": 4.23
},
{
"text": "braces to say this line of code in that",
"start": 1159.17,
"duration": 3.78
},
{
"text": "line of code that's inside of the if",
"start": 1161.18,
"duration": 3.84
},
{
"text": "expression or that's inside of the else",
"start": 1162.95,
"duration": 5.04
},
{
"text": "expression for example so let's go ahead",
"start": 1165.02,
"duration": 4.47
},
{
"text": "and try this now I can go ahead and open",
"start": 1167.99,
"duration": 3.29
},
{
"text": "hello dot HTML",
"start": 1169.49,
"duration": 4.26
},
{
"text": "refresh it it currently says hello with",
"start": 1171.28,
"duration": 5.25
},
{
"text": "a button that says click here and now",
"start": 1173.75,
"duration": 5.79
},
{
"text": "when I click here hello changes to",
"start": 1176.53,
"duration": 5.2
},
{
"text": "goodbye and when I click here again",
"start": 1179.54,
"duration": 4.5
},
{
"text": "goodbye changes back to hello and every",
"start": 1181.73,
"duration": 3.99
},
{
"text": "time I click the button it's going to",
"start": 1184.04,
"duration": 3.06
},
{
"text": "alternate between hello and goodbye",
"start": 1185.72,
"duration": 3.24
},
{
"text": "because we either get caught in the if",
"start": 1187.1,
"duration": 4.35
},
{
"text": "expression or we get caught in the else",
"start": 1188.96,
"duration": 5.19
},
{
"text": "expression now there are a couple of",
"start": 1191.45,
"duration": 3.93
},
{
"text": "places where you might look at this and",
"start": 1194.15,
"duration": 2.73
},
{
"text": "notice that maybe this isn't as",
"start": 1195.38,
"duration": 3.45
},
{
"text": "efficient as this code could potentially",
"start": 1196.88,
"duration": 4.08
},
{
"text": "be and recall that every time we run",
"start": 1198.83,
"duration": 4.77
},
{
"text": "document query selector to say go ahead",
"start": 1200.96,
"duration": 4.2
},
{
"text": "and try and find a particular HTML",
"start": 1203.6,
"duration": 4.17
},
{
"text": "element for me it's going to look",
"start": 1205.16,
"duration": 4.53
},
{
"text": "through that page trying to find the h1",
"start": 1207.77,
"duration": 3.63
},
{
"text": "element and it turns out that right now",
"start": 1209.69,
"duration": 4.17
},
{
"text": "we have three separate calls to query",
"start": 1211.4,
"duration": 3.99
},
{
"text": "selector even though only two of them",
"start": 1213.86,
"duration": 3.0
},
{
"text": "will ever run on any given instance of",
"start": 1215.39,
"duration": 2.66
},
{
"text": "the function but we",
"start": 1216.86,
"duration": 3.23
},
{
"text": "document a query selector then we call",
"start": 1218.05,
"duration": 4.56
},
{
"text": "it again inside of the if expression we",
"start": 1220.09,
"duration": 4.53
},
{
"text": "can probably improve the design of this",
"start": 1222.61,
"duration": 4.44
},
{
"text": "page by factoring that out by just",
"start": 1224.62,
"duration": 4.65
},
{
"text": "looking for the h1 element once and then",
"start": 1227.05,
"duration": 4.41
},
{
"text": "manipulating it and checking it using",
"start": 1229.27,
"duration": 4.5
},
{
"text": "that element that we have found and to",
"start": 1231.46,
"duration": 4.38
},
{
"text": "do that we can store an element inside",
"start": 1233.77,
"duration": 3.72
},
{
"text": "of a variable in the same way that a",
"start": 1235.84,
"duration": 3.72
},
{
"text": "variable can store a number like a",
"start": 1237.49,
"duration": 4.35
},
{
"text": "counter or a string like hello world it",
"start": 1239.56,
"duration": 4.68
},
{
"text": "can also store other values like an HTML",
"start": 1241.84,
"duration": 5.04
},
{
"text": "element that we get back from document",
"start": 1244.24,
"duration": 4.77
},
{
"text": "dog query selector so I could say",
"start": 1246.88,
"duration": 6.54
},
{
"text": "something like let heading we're heading",
"start": 1249.01,
"duration": 6.63
},
{
"text": "is just the name of a variable the equal",
"start": 1253.42,
"duration": 5.85
},
{
"text": "to document query selector h1 for",
"start": 1255.64,
"duration": 5.94
},
{
"text": "instance find the h1 element save it",
"start": 1259.27,
"duration": 3.84
},
{
"text": "inside of a variable called heading and",
"start": 1261.58,
"duration": 4.32
},
{
"text": "now rather than document query selector",
"start": 1263.11,
"duration": 4.83
},
{
"text": "each one all the time I can just say if",
"start": 1265.9,
"duration": 4.23
},
{
"text": "the headings inner HTML is hello",
"start": 1267.94,
"duration": 4.98
},
{
"text": "then set the headings inner HTML to good",
"start": 1270.13,
"duration": 3.21
},
{
"text": "bye",
"start": 1272.92,
"duration": 2.91
},
{
"text": "otherwise I set the headings inner HTML",
"start": 1273.34,
"duration": 3.51
},
{
"text": "to hello",
"start": 1275.83,
"duration": 2.46
},
{
"text": "so I've improved the efficiency of the",
"start": 1276.85,
"duration": 3.36
},
{
"text": "program but also reduce the number of",
"start": 1278.29,
"duration": 3.36
},
{
"text": "characters of code that I've had to",
"start": 1280.21,
"duration": 3.0
},
{
"text": "write my lines are now much shorter a",
"start": 1281.65,
"duration": 3.39
},
{
"text": "little bit easier to read this we would",
"start": 1283.21,
"duration": 4.11
},
{
"text": "consider to be an improvement in design",
"start": 1285.04,
"duration": 4.17
},
{
"text": "and it turns out there's one other",
"start": 1287.32,
"duration": 4.47
},
{
"text": "improvement we can make here too that we",
"start": 1289.21,
"duration": 4.74
},
{
"text": "can define a variable like let something",
"start": 1291.79,
"duration": 4.11
},
{
"text": "equal something else but it turns out",
"start": 1293.95,
"duration": 3.48
},
{
"text": "that JavaScript gives us a couple of",
"start": 1295.9,
"duration": 4.14
},
{
"text": "ways to define a variable and if we're",
"start": 1297.43,
"duration": 4.56
},
{
"text": "going to be creating a variable whose",
"start": 1300.04,
"duration": 4.38
},
{
"text": "value is never going to change we're",
"start": 1301.99,
"duration": 4.26
},
{
"text": "never going to reassign the variable",
"start": 1304.42,
"duration": 4.17
},
{
"text": "name to something else then instead of",
"start": 1306.25,
"duration": 4.62
},
{
"text": "let we can enforce that it's never going",
"start": 1308.59,
"duration": 5.31
},
{
"text": "to change by calling it a Const variable",
"start": 1310.87,
"duration": 5.91
},
{
"text": "so Const heading equals document query",
"start": 1313.9,
"duration": 5.31
},
{
"text": "selector h1 means I am going to create a",
"start": 1316.78,
"duration": 4.44
},
{
"text": "variable called heading setting it equal",
"start": 1319.21,
"duration": 4.35
},
{
"text": "to the result of document query selector",
"start": 1321.22,
"duration": 5.82
},
{
"text": "h1 and never again will I change what",
"start": 1323.56,
"duration": 5.1
},
{
"text": "heading is equal to I will never have",
"start": 1327.04,
"duration": 3.0
},
{
"text": "another line of code that says heading",
"start": 1328.66,
"duration": 3.63
},
{
"text": "equals something else because it is",
"start": 1330.04,
"duration": 3.87
},
{
"text": "constant and JavaScript will then",
"start": 1332.29,
"duration": 3.27
},
{
"text": "enforce that this variable should not",
"start": 1333.91,
"duration": 3.72
},
{
"text": "change and if ever I do try to change it",
"start": 1335.56,
"duration": 3.66
},
{
"text": "javascript will give me an error and",
"start": 1337.63,
"duration": 3.84
},
{
"text": "this can just be helpful to prevent",
"start": 1339.22,
"duration": 4.14
},
{
"text": "against possible unintended behavior",
"start": 1341.47,
"duration": 3.81
},
{
"text": "that if you know you have a variable it",
"start": 1343.36,
"duration": 3.69
},
{
"text": "is never going to change it's often good",
"start": 1345.28,
"duration": 4.71
},
{
"text": "designed to label it as a constable so",
"start": 1347.05,
"duration": 4.29
},
{
"text": "that you and other people looking at",
"start": 1349.99,
"duration": 1.75
},
{
"text": "your code",
"start": 1351.34,
"duration": 2.41
},
{
"text": "know that that is never going to have a",
"start": 1351.74,
"duration": 5.25
},
{
"text": "value that gets changed later on so this",
"start": 1353.75,
"duration": 5.7
},
{
"text": "then will behave the same way where it",
"start": 1356.99,
"duration": 4.38
},
{
"text": "says hello but I can toggle it back and",
"start": 1359.45,
"duration": 4.74
},
{
"text": "forth changing it to goodbye and then",
"start": 1361.37,
"duration": 5.67
},
{
"text": "changing it back to hello again and so",
"start": 1364.19,
"duration": 4.83
},
{
"text": "now using this ability this ability to",
"start": 1367.04,
"duration": 4.019
},
{
"text": "manipulate the dawn we can go back to",
"start": 1369.02,
"duration": 4.02
},
{
"text": "our counter program and actually improve",
"start": 1371.059,
"duration": 4.471
},
{
"text": "upon it that right now the counter",
"start": 1373.04,
"duration": 5.28
},
{
"text": "program I count and it displays an alert",
"start": 1375.53,
"duration": 4.59
},
{
"text": "that says 1 I count and it displays an",
"start": 1378.32,
"duration": 3.9
},
{
"text": "alert that says 2 I can probably do a",
"start": 1380.12,
"duration": 4.23
},
{
"text": "little bit better than that by instead",
"start": 1382.22,
"duration": 4.11
},
{
"text": "of displaying an alert actually",
"start": 1384.35,
"duration": 4.86
},
{
"text": "manipulating the Dom in some way that I",
"start": 1386.33,
"duration": 4.86
},
{
"text": "would like to have this h1 this big",
"start": 1389.21,
"duration": 3.81
},
{
"text": "heading at the top instead of starting",
"start": 1391.19,
"duration": 3.989
},
{
"text": "up by saying hello let's have it start",
"start": 1393.02,
"duration": 5.25
},
{
"text": "out by saying 0 for example just some",
"start": 1395.179,
"duration": 5.821
},
{
"text": "initial value for the counter and now",
"start": 1398.27,
"duration": 4.26
},
{
"text": "when I increment the value of counter",
"start": 1401.0,
"duration": 3.63
},
{
"text": "rather than display an alert that just",
"start": 1402.53,
"duration": 3.779
},
{
"text": "tells me the value of the counter in an",
"start": 1404.63,
"duration": 4.26
},
{
"text": "alert I'm going to instead say document",
"start": 1406.309,
"duration": 7.671
},
{
"text": "query selector h1 . innerhtml",
"start": 1408.89,
"duration": 10.05
},
{
"text": "equals counter where i'm saying find the",
"start": 1413.98,
"duration": 7.42
},
{
"text": "h1 element updated innerhtml",
"start": 1418.94,
"duration": 4.8
},
{
"text": "set it equal to whatever the value of",
"start": 1421.4,
"duration": 5.1
},
{
"text": "the variable counter happens to be such",
"start": 1423.74,
"duration": 4.86
},
{
"text": "that now if i refresh this page the",
"start": 1426.5,
"duration": 3.96
},
{
"text": "value of this h1 initially is 0 that's",
"start": 1428.6,
"duration": 3.66
},
{
"text": "the initial value but every time I click",
"start": 1430.46,
"duration": 4.05
},
{
"text": "count we're going to update the contents",
"start": 1432.26,
"duration": 4.26
},
{
"text": "of that h1 element and this time setting",
"start": 1434.51,
"duration": 5.22
},
{
"text": "it to 1 2 3 4 and so forth every time I",
"start": 1436.52,
"duration": 4.74
},
{
"text": "click the count button it's going to",
"start": 1439.73,
"duration": 3.18
},
{
"text": "increment the value of the variable as",
"start": 1441.26,
"duration": 3.93
},
{
"text": "well as manipulate the Dom actually",
"start": 1442.91,
"duration": 5.82
},
{
"text": "making changes in order to produce the",
"start": 1445.19,
"duration": 5.489
},
{
"text": "effect that I want to see on this actual",
"start": 1448.73,
"duration": 5.07
},
{
"text": "page and we can begin to add additional",
"start": 1450.679,
"duration": 4.861
},
{
"text": "logic to this as well maybe I do",
"start": 1453.8,
"duration": 3.78
},
{
"text": "occasionally want an alert but I don't",
"start": 1455.54,
"duration": 3.96
},
{
"text": "want an alert every single time I could",
"start": 1457.58,
"duration": 3.39
},
{
"text": "add a condition I could say something",
"start": 1459.5,
"duration": 2.94
},
{
"text": "like if I only want to display an alert",
"start": 1460.97,
"duration": 3.69
},
{
"text": "every time I count to a multiple of 10",
"start": 1462.44,
"duration": 4.29
},
{
"text": "like 10 and 20 and 30 and 40 and 50 and",
"start": 1464.66,
"duration": 4.14
},
{
"text": "so forth I could add a condition that",
"start": 1466.73,
"duration": 6.06
},
{
"text": "says that if counter mod 10 and mod just",
"start": 1468.8,
"duration": 6.09
},
{
"text": "gets me remainder when you divide by 10",
"start": 1472.79,
"duration": 3.6
},
{
"text": "so if you take the counter divide it by",
"start": 1474.89,
"duration": 4.44
},
{
"text": "10 if the remainder is 0 when I divide",
"start": 1476.39,
"duration": 4.919
},
{
"text": "by 10 well that means counter is a",
"start": 1479.33,
"duration": 4.2
},
{
"text": "multiple of 10 and so I can now display",
"start": 1481.309,
"duration": 4.681
},
{
"text": "an alert where I can display annele",
"start": 1483.53,
"duration": 4.529
},
{
"text": "that says like I want to say something",
"start": 1485.99,
"duration": 4.53
},
{
"text": "like the counter is now 10 or the",
"start": 1488.059,
"duration": 4.651
},
{
"text": "counter is now 20 and in order to do",
"start": 1490.52,
"duration": 3.87
},
{
"text": "that what I really want to do is have",
"start": 1492.71,
"duration": 5.31
},
{
"text": "some way of plugging in a variable into",
"start": 1494.39,
"duration": 6.57
},
{
"text": "a string inside of JavaScript and in",
"start": 1498.02,
"duration": 4.53
},
{
"text": "Python the way we would have done this",
"start": 1500.96,
"duration": 3.9
},
{
"text": "is by you appending f4 prepending F in",
"start": 1502.55,
"duration": 3.629
},
{
"text": "front of the string to create a",
"start": 1504.86,
"duration": 3.42
},
{
"text": "formatted string and then I would have",
"start": 1506.179,
"duration": 4.621
},
{
"text": "said something like the count is now and",
"start": 1508.28,
"duration": 5.22
},
{
"text": "then I'd use curly braces to say go",
"start": 1510.8,
"duration": 4.41
},
{
"text": "ahead and print out the value of counter",
"start": 1513.5,
"duration": 3.809
},
{
"text": "so this f4 formatted string followed by",
"start": 1515.21,
"duration": 3.66
},
{
"text": "this string would have been the way in",
"start": 1517.309,
"duration": 2.941
},
{
"text": "python that we would have done this",
"start": 1518.87,
"duration": 3.24
},
{
"text": "turns out javascript does the same thing",
"start": 1520.25,
"duration": 3.87
},
{
"text": "just with slightly different syntax it",
"start": 1522.11,
"duration": 4.98
},
{
"text": "doesn't use F instead instead of using",
"start": 1524.12,
"duration": 4.74
},
{
"text": "the regular quotation marks whether the",
"start": 1527.09,
"duration": 3.469
},
{
"text": "single or double quotation marks",
"start": 1528.86,
"duration": 4.47
},
{
"text": "JavaScript uses these backticks",
"start": 1530.559,
"duration": 4.841
},
{
"text": "which are usually located above the tab",
"start": 1533.33,
"duration": 5.37
},
{
"text": "key on a standard u.s. keyboard and this",
"start": 1535.4,
"duration": 5.01
},
{
"text": "is going to create what JavaScript calls",
"start": 1538.7,
"duration": 3.72
},
{
"text": "a template literal where I can then",
"start": 1540.41,
"duration": 3.39
},
{
"text": "substitute the value of a variable",
"start": 1542.42,
"duration": 3.96
},
{
"text": "somewhere inside of this template and",
"start": 1543.8,
"duration": 4.59
},
{
"text": "then in order to actually do the",
"start": 1546.38,
"duration": 4.29
},
{
"text": "substitution while Python uses double",
"start": 1548.39,
"duration": 4.26
},
{
"text": "curly braces to say plug in the value of",
"start": 1550.67,
"duration": 3.9
},
{
"text": "counter right here javascript does",
"start": 1552.65,
"duration": 3.54
},
{
"text": "something similar it also uses double",
"start": 1554.57,
"duration": 3.3
},
{
"text": "curly braces but there needs to be a",
"start": 1556.19,
"duration": 3.36
},
{
"text": "dollar sign in front of it the dollar",
"start": 1557.87,
"duration": 3.54
},
{
"text": "sign and then the dollar double curly",
"start": 1559.55,
"duration": 3.99
},
{
"text": "braces we can go ahead and plug in the",
"start": 1561.41,
"duration": 5.19
},
{
"text": "value of a variable there so this then",
"start": 1563.54,
"duration": 5.55
},
{
"text": "is a template literal where every time",
"start": 1566.6,
"duration": 4.44
},
{
"text": "we get to a multiple of ten we're going",
"start": 1569.09,
"duration": 3.51
},
{
"text": "to display an alert that says the count",
"start": 1571.04,
"duration": 4.38
},
{
"text": "is now and then this dollar sign curly",
"start": 1572.6,
"duration": 5.1
},
{
"text": "brace means actually plug in whatever",
"start": 1575.42,
"duration": 5.009
},
{
"text": "the value of counter happens to be right",
"start": 1577.7,
"duration": 5.609
},
{
"text": "there so now if I go ahead and refresh",
"start": 1580.429,
"duration": 5.671
},
{
"text": "counter it starts at zero I can count 3",
"start": 1583.309,
"duration": 5.671
},
{
"text": "4 5 6 7 8 9 but when I get to 10 then I",
"start": 1586.1,
"duration": 4.86
},
{
"text": "get an alert that says the count is now",
"start": 1588.98,
"duration": 4.65
},
{
"text": "10 and then I see the result update on",
"start": 1590.96,
"duration": 5.25
},
{
"text": "the page and so that template literal",
"start": 1593.63,
"duration": 5.07
},
{
"text": "can allow us to combine variables and",
"start": 1596.21,
"duration": 4.56
},
{
"text": "strings in order to generate new strings",
"start": 1598.7,
"duration": 4.74
},
{
"text": "that are able to represent data inside",
"start": 1600.77,
"duration": 6.0
},
{
"text": "of them as well so now what improvements",
"start": 1603.44,
"duration": 4.98
},
{
"text": "can we begin to make it what changes can",
"start": 1606.77,
"duration": 3.0
},
{
"text": "we make to this to improve upon the",
"start": 1608.42,
"duration": 3.3
},
{
"text": "design of it well one thing especially",
"start": 1609.77,
"duration": 3.78
},
{
"text": "as our programs get a little bit more",
"start": 1611.72,
"duration": 3.089
},
{
"text": "sophisticated a little bit more",
"start": 1613.55,
"duration": 3.509
},
{
"text": "complicated is that we often don't want",
"start": 1614.809,
"duration": 5.521
},
{
"text": "to be intermingling our JavaScript code",
"start": 1617.059,
"duration": 5.401
},
{
"text": "with the contents of our HTML the down",
"start": 1620.33,
"duration": 4.14
},
{
"text": "here we have button on click equals",
"start": 1622.46,
"duration": 3.87
},
{
"text": "count this name of this function and",
"start": 1624.47,
"duration": 3.9
},
{
"text": "especially as our page starts to get",
"start": 1626.33,
"duration": 3.93
},
{
"text": "more complicated it's going to start to",
"start": 1628.37,
"duration": 3.689
},
{
"text": "get a little bit annoying if we're",
"start": 1630.26,
"duration": 3.63
},
{
"text": "constantly having to maintain a little",
"start": 1632.059,
"duration": 3.301
},
{
"text": "bit of JavaScript code like making a",
"start": 1633.89,
"duration": 3.539
},
{
"text": "call to a function inside of our HTML",
"start": 1635.36,
"duration": 3.689
},
{
"text": "we'll see a little bit later there are",
"start": 1637.429,
"duration": 3.151
},
{
"text": "other paradigms that actually encourage",
"start": 1639.049,
"duration": 3.691
},
{
"text": "this type of thing but right now it can",
"start": 1640.58,
"duration": 4.05
},
{
"text": "start to get a little poorly designed if",
"start": 1642.74,
"duration": 3.84
},
{
"text": "we'd really like to separate all of our",
"start": 1644.63,
"duration": 4.139
},
{
"text": "JavaScript related code from all of the",
"start": 1646.58,
"duration": 4.55
},
{
"text": "HTML the general structure of our page",
"start": 1648.769,
"duration": 4.77
},
{
"text": "and so there are ways we can begin to do",
"start": 1651.13,
"duration": 4.98
},
{
"text": "that as well I can add an event listener",
"start": 1653.539,
"duration": 5.88
},
{
"text": "inside of JavaScript to that I can say",
"start": 1656.11,
"duration": 7.419
},
{
"text": "something like document dot query",
"start": 1659.419,
"duration": 8.911
},
{
"text": "selector button and then I can say dot",
"start": 1663.529,
"duration": 10.081
},
{
"text": "on click equals count so what's going on",
"start": 1668.33,
"duration": 7.26
},
{
"text": "here and I can do this instead of this",
"start": 1673.61,
"duration": 3.96
},
{
"text": "on click equals count what I'm now",
"start": 1675.59,
"duration": 4.829
},
{
"text": "saying is document query selector button",
"start": 1677.57,
"duration": 5.219
},
{
"text": "find me the button on the page and turns",
"start": 1680.419,
"duration": 3.781
},
{
"text": "out there's only one button here so it's",
"start": 1682.789,
"duration": 2.64
},
{
"text": "fine though if there were more I might",
"start": 1684.2,
"duration": 2.55
},
{
"text": "have to be a little bit more specific",
"start": 1685.429,
"duration": 4.23
},
{
"text": "but once I get that button then I'm",
"start": 1686.75,
"duration": 4.799
},
{
"text": "going to access it's on click property",
"start": 1689.659,
"duration": 4.921
},
{
"text": "and I'm going to set it equal to count",
"start": 1691.549,
"duration": 5.73
},
{
"text": "and what does count count is the name of",
"start": 1694.58,
"duration": 4.86
},
{
"text": "a function count is itself a function",
"start": 1697.279,
"duration": 4.801
},
{
"text": "and so what I'm here saying is I would",
"start": 1699.44,
"duration": 4.92
},
{
"text": "like to set the value of the onclick",
"start": 1702.08,
"duration": 4.29
},
{
"text": "property of the button equal to count",
"start": 1704.36,
"duration": 3.539
},
{
"text": "the count is the function that should",
"start": 1706.37,
"duration": 4.95
},
{
"text": "run when the button is clicked on and",
"start": 1707.899,
"duration": 5.671
},
{
"text": "notice that I am not actually calling",
"start": 1711.32,
"duration": 4.05
},
{
"text": "the function it's not count and then",
"start": 1713.57,
"duration": 3.479
},
{
"text": "parentheses which were being run the",
"start": 1715.37,
"duration": 3.75
},
{
"text": "count function and then get its return",
"start": 1717.049,
"duration": 3.931
},
{
"text": "value and use that as the value for",
"start": 1719.12,
"duration": 4.289
},
{
"text": "onclick I'm just setting on click equal",
"start": 1720.98,
"duration": 4.949
},
{
"text": "literally to the count function itself",
"start": 1723.409,
"duration": 3.87
},
{
"text": "without actually calling the function",
"start": 1725.929,
"duration": 3.84
},
{
"text": "and what this is going to do is it is",
"start": 1727.279,
"duration": 4.11
},
{
"text": "going to say when the button is clicked",
"start": 1729.769,
"duration": 3.931
},
{
"text": "on then and only then should you",
"start": 1731.389,
"duration": 4.41
},
{
"text": "actually run this count function and",
"start": 1733.7,
"duration": 3.06
},
{
"text": "we're not going to run the count",
"start": 1735.799,
"duration": 4.201
},
{
"text": "function until that button actually gets",
"start": 1736.76,
"duration": 5.25
},
{
"text": "clicked on and so in JavaScript",
"start": 1740.0,
"duration": 4.679
},
{
"text": "functions can be treated as values of",
"start": 1742.01,
"duration": 4.799
},
{
"text": "their own just as you can set a variable",
"start": 1744.679,
"duration": 3.99
},
{
"text": "equal to a string just as even set a",
"start": 1746.809,
"duration": 3.75
},
{
"text": "variable equal to an integer just as you",
"start": 1748.669,
"duration": 3.811
},
{
"text": "can set a variable equal to like an HTML",
"start": 1750.559,
"duration": 3.601
},
{
"text": "element like the result of document",
"start": 1752.48,
"duration": 3.99
},
{
"text": "query selector you can also set a",
"start": 1754.16,
"duration": 4.83
},
{
"text": "variable equal to a function something",
"start": 1756.47,
"duration": 4.59
},
{
"text": "like count and passed that around as a",
"start": 1758.99,
"duration": 4.56
},
{
"text": "value just as you could with any other",
"start": 1761.06,
"duration": 3.99
},
{
"text": "value and this is a paradigm we",
"start": 1763.55,
"duration": 3.09
},
{
"text": "generally call functional programming",
"start": 1765.05,
"duration": 4.35
},
{
"text": "where we have functions as values of",
"start": 1766.64,
"duration": 4.14
},
{
"text": "their own things that we can reassign",
"start": 1769.4,
"duration": 3.6
},
{
"text": "things that we can manipulate just as we",
"start": 1770.78,
"duration": 6.0
},
{
"text": "could have any other value so now I can",
"start": 1773.0,
"duration": 5.22
},
{
"text": "try and run this program by going ahead",
"start": 1776.78,
"duration": 3.39
},
{
"text": "and refreshing the page I'll refresh it",
"start": 1778.22,
"duration": 4.92
},
{
"text": "at zero I press count and alright",
"start": 1780.17,
"duration": 4.98
},
{
"text": "nothing seems to be happening it's still",
"start": 1783.14,
"duration": 4.32
},
{
"text": "zero I want it to be counting but it",
"start": 1785.15,
"duration": 4.35
},
{
"text": "doesn't seem to be working so why not",
"start": 1787.46,
"duration": 3.81
},
{
"text": "any time you run into problems in",
"start": 1789.5,
"duration": 3.0
},
{
"text": "JavaScript where you're not getting the",
"start": 1791.27,
"duration": 2.94
},
{
"text": "behavior you want often it can be",
"start": 1792.5,
"duration": 3.21
},
{
"text": "helpful to look at the JavaScript",
"start": 1794.21,
"duration": 3.57
},
{
"text": "console where the JavaScript console is",
"start": 1795.71,
"duration": 3.84
},
{
"text": "the equivalent of like the terminal",
"start": 1797.78,
"duration": 3.0
},
{
"text": "window and when you're running your",
"start": 1799.55,
"duration": 3.06
},
{
"text": "Django application in Python that would",
"start": 1800.78,
"duration": 3.51
},
{
"text": "display any error messages the",
"start": 1802.61,
"duration": 3.69
},
{
"text": "JavaScript console will display any of",
"start": 1804.29,
"duration": 3.84
},
{
"text": "the JavaScript logging information and",
"start": 1806.3,
"duration": 4.68
},
{
"text": "error messages as well in chrome I can",
"start": 1808.13,
"duration": 4.74
},
{
"text": "get to it if I first go ahead and go to",
"start": 1810.98,
"duration": 4.86
},
{
"text": "inspect and then just open up the",
"start": 1812.87,
"duration": 5.55
},
{
"text": "console tab here and all right we seem",
"start": 1815.84,
"duration": 4.2
},
{
"text": "to have some sort of error here it's an",
"start": 1818.42,
"duration": 4.59
},
{
"text": "uncaught type error that says we cannot",
"start": 1820.04,
"duration": 7.17
},
{
"text": "set property on click of no encounter",
"start": 1823.01,
"duration": 7.11
},
{
"text": "dot HTML line 18 so that will generally",
"start": 1827.21,
"duration": 4.38
},
{
"text": "tell you where the error is coming from",
"start": 1830.12,
"duration": 3.87
},
{
"text": "it's coming from counter HTML on line 18",
"start": 1831.59,
"duration": 4.74
},
{
"text": "and the problem seems to be but I'm",
"start": 1833.99,
"duration": 4.47
},
{
"text": "trying to access the on click property",
"start": 1836.33,
"duration": 5.07
},
{
"text": "of no and no is JavaScript way of",
"start": 1838.46,
"duration": 4.89
},
{
"text": "expressing like nothing some object that",
"start": 1841.4,
"duration": 5.07
},
{
"text": "doesn't exist so somehow I'm trying to",
"start": 1843.35,
"duration": 5.1
},
{
"text": "set the onclick property of no well",
"start": 1846.47,
"duration": 3.9
},
{
"text": "let's see what's going on on line 18 and",
"start": 1848.45,
"duration": 4.14
},
{
"text": "see if we can figure out what's",
"start": 1850.37,
"duration": 2.91
},
{
"text": "happening there",
"start": 1852.59,
"duration": 3.24
},
{
"text": "well alright here is line 18 where I say",
"start": 1853.28,
"duration": 4.14
},
{
"text": "document dot query selector button",
"start": 1855.83,
"duration": 4.08
},
{
"text": "setting it's on click property equal to",
"start": 1857.42,
"duration": 4.86
},
{
"text": "count and now what seems to be the",
"start": 1859.91,
"duration": 4.32
},
{
"text": "problem here well the error message was",
"start": 1862.28,
"duration": 4.26
},
{
"text": "that I was trying to modify the onclick",
"start": 1864.23,
"duration": 4.92
},
{
"text": "property of no well here then is the",
"start": 1866.54,
"duration": 4.86
},
{
"text": "onclick property so why would this",
"start": 1869.15,
"duration": 4.62
},
{
"text": "document query selector button be",
"start": 1871.4,
"duration": 4.65
},
{
"text": "returning or giving me an output of no",
"start": 1873.77,
"duration": 4.59
},
{
"text": "well it turns out the document dot query",
"start": 1876.05,
"duration": 4.35
},
{
"text": "selector will return null if it's not",
"start": 1878.36,
"duration": 4.23
},
{
"text": "able to find something if I try and find",
"start": 1880.4,
"duration": 4.08
},
{
"text": "a button but it's not able to find a",
"start": 1882.59,
"duration": 3.57
},
{
"text": "button well this seems a little bit",
"start": 1884.48,
"duration": 3.12
},
{
"text": "strange because there's a button down",
"start": 1886.16,
"duration": 1.77
},
{
"text": "here",
"start": 1887.6,
"duration": 3.66
},
{
"text": "24 that I'd like for my JavaScript code",
"start": 1887.93,
"duration": 5.28
},
{
"text": "to be able to find when it runs query",
"start": 1891.26,
"duration": 4.23
},
{
"text": "selector and tries to find the button as",
"start": 1893.21,
"duration": 4.08
},
{
"text": "it turns out this is a bit of the quirk",
"start": 1895.49,
"duration": 3.09
},
{
"text": "of the way the browser is going to work",
"start": 1897.29,
"duration": 3.09
},
{
"text": "but if the browser is running our code",
"start": 1898.58,
"duration": 3.66
},
{
"text": "from top to bottom just reading it from",
"start": 1900.38,
"duration": 4.08
},
{
"text": "line one on and on then it's going to",
"start": 1902.24,
"duration": 4.68
},
{
"text": "get to line 18 where I said document",
"start": 1904.46,
"duration": 4.32
},
{
"text": "query selector button onclick equals",
"start": 1906.92,
"duration": 4.11
},
{
"text": "count and it's going to try and find a",
"start": 1908.78,
"duration": 4.65
},
{
"text": "button on line 18 but the button doesn't",
"start": 1911.03,
"duration": 5.01
},
{
"text": "show up in my HTML page until much",
"start": 1913.43,
"duration": 4.8
},
{
"text": "further down in the page so at this",
"start": 1916.04,
"duration": 3.75
},
{
"text": "point when we get to this line of",
"start": 1918.23,
"duration": 3.57
},
{
"text": "JavaScript javascript is looking for the",
"start": 1919.79,
"duration": 4.29
},
{
"text": "button but the Dom the body of the page",
"start": 1921.8,
"duration": 4.65
},
{
"text": "hasn't finished loading yet the content",
"start": 1924.08,
"duration": 4.56
},
{
"text": "of the Dom has not yet loaded and as a",
"start": 1926.45,
"duration": 4.35
},
{
"text": "result we're not able to find this",
"start": 1928.64,
"duration": 4.08
},
{
"text": "button so how do we solve this problem",
"start": 1930.8,
"duration": 3.6
},
{
"text": "how do we get it so we actually are able",
"start": 1932.72,
"duration": 3.87
},
{
"text": "to like ask for the button and actually",
"start": 1934.4,
"duration": 3.81
},
{
"text": "get the button well it turns out there",
"start": 1936.59,
"duration": 2.97
},
{
"text": "are a couple of strategies we could use",
"start": 1938.21,
"duration": 4.02
},
{
"text": "one would be take the script tag and go",
"start": 1939.56,
"duration": 4.56
},
{
"text": "ahead and just move it to the bottom",
"start": 1942.23,
"duration": 3.84
},
{
"text": "section of the body so that after we've",
"start": 1944.12,
"duration": 3.15
},
{
"text": "already defined the button that says",
"start": 1946.07,
"duration": 3.0
},
{
"text": "count then we have the script tag that",
"start": 1947.27,
"duration": 3.54
},
{
"text": "then says alright go ahead and now find",
"start": 1949.07,
"duration": 3.33
},
{
"text": "the button and now we'll be able to find",
"start": 1950.81,
"duration": 3.75
},
{
"text": "it it turns out another way and perhaps",
"start": 1952.4,
"duration": 5.34
},
{
"text": "a more common way is to instead add yet",
"start": 1954.56,
"duration": 5.52
},
{
"text": "another event listener and we're gonna",
"start": 1957.74,
"duration": 3.96
},
{
"text": "add an event listener not to the button",
"start": 1960.08,
"duration": 4.11
},
{
"text": "but to the entire document where",
"start": 1961.7,
"duration": 4.32
},
{
"text": "document is a variable built into this",
"start": 1964.19,
"duration": 3.42
},
{
"text": "JavaScript that we have access to on the",
"start": 1966.02,
"duration": 3.87
},
{
"text": "web page that just refers to this entire",
"start": 1967.61,
"duration": 4.56
},
{
"text": "web document where I've used document",
"start": 1969.89,
"duration": 4.44
},
{
"text": "query selector already to look through",
"start": 1972.17,
"duration": 3.75
},
{
"text": "the whole web document trying to find a",
"start": 1974.33,
"duration": 3.63
},
{
"text": "button or trying to find an h1 tag for",
"start": 1975.92,
"duration": 4.77
},
{
"text": "example but I can also add an event",
"start": 1977.96,
"duration": 5.64
},
{
"text": "listener to the document itself and in",
"start": 1980.69,
"duration": 5.19
},
{
"text": "order to do that I can say document dot",
"start": 1983.6,
"duration": 6.66
},
{
"text": "add event listener and when I call add",
"start": 1985.88,
"duration": 6.12
},
{
"text": "event listener and I can do this on any",
"start": 1990.26,
"duration": 3.69
},
{
"text": "HTML element not just the document but I",
"start": 1992.0,
"duration": 3.66
},
{
"text": "could run this function on a button or",
"start": 1993.95,
"duration": 3.48
},
{
"text": "on an h1 element or any other HTML",
"start": 1995.66,
"duration": 3.72
},
{
"text": "element add event listener will",
"start": 1997.43,
"duration": 4.47
},
{
"text": "generally take two arguments where the",
"start": 1999.38,
"duration": 5.04
},
{
"text": "first is what event I want to listen for",
"start": 2001.9,
"duration": 4.35
},
{
"text": "the event could be something like click",
"start": 2004.42,
"duration": 3.69
},
{
"text": "when I click on the document it could be",
"start": 2006.25,
"duration": 4.44
},
{
"text": "something like when I scroll through a",
"start": 2008.11,
"duration": 4.53
},
{
"text": "page for example but with the event I'm",
"start": 2010.69,
"duration": 3.39
},
{
"text": "going to listen for is a particularly",
"start": 2012.64,
"duration": 4.17
},
{
"text": "special event called Dom content loaded",
"start": 2014.08,
"duration": 6.54
},
{
"text": "and the Dom content loaded event is an",
"start": 2016.81,
"duration": 5.01
},
{
"text": "event that is going to be",
"start": 2020.62,
"duration": 3.75
},
{
"text": "hired or triggered when the Dom the",
"start": 2021.82,
"duration": 4.11
},
{
"text": "document object model the structure of",
"start": 2024.37,
"duration": 3.84
},
{
"text": "the page is done loading when all of the",
"start": 2025.93,
"duration": 3.48
},
{
"text": "elements on the page are done loading",
"start": 2028.21,
"duration": 3.63
},
{
"text": "the Dom content has been loaded and then",
"start": 2029.41,
"duration": 4.98
},
{
"text": "if I attach an event listener to it you",
"start": 2031.84,
"duration": 4.35
},
{
"text": "know run whatever code I want to run",
"start": 2034.39,
"duration": 4.23
},
{
"text": "that should only run after the Dom is",
"start": 2036.19,
"duration": 4.59
},
{
"text": "fully loaded after all of the content on",
"start": 2038.62,
"duration": 5.04
},
{
"text": "the page has then been loaded and the",
"start": 2040.78,
"duration": 5.28
},
{
"text": "second argument to an event listener is",
"start": 2043.66,
"duration": 5.73
},
{
"text": "what function should run once the event",
"start": 2046.06,
"duration": 4.86
},
{
"text": "actually happens when the Dom content",
"start": 2049.39,
"duration": 3.72
},
{
"text": "loaded does happen so I could pass in",
"start": 2050.92,
"duration": 4.2
},
{
"text": "the name of a function if I had the name",
"start": 2053.11,
"duration": 3.87
},
{
"text": "of a function that I wanted to pass in",
"start": 2055.12,
"duration": 4.32
},
{
"text": "but alternatively JavaScript allows me",
"start": 2056.98,
"duration": 5.31
},
{
"text": "to just directly write a function here",
"start": 2059.44,
"duration": 5.28
},
{
"text": "in the argument to add event listener I",
"start": 2062.29,
"duration": 4.92
},
{
"text": "can just say function and then a set of",
"start": 2064.72,
"duration": 3.84
},
{
"text": "parentheses to mean the function doesn't",
"start": 2067.21,
"duration": 3.69
},
{
"text": "take any input and then in curly braces",
"start": 2068.56,
"duration": 4.89
},
{
"text": "I can include the body of the function",
"start": 2070.9,
"duration": 6.39
},
{
"text": "right here as the second argument to add",
"start": 2073.45,
"duration": 5.4
},
{
"text": "event listener and this is a little bit",
"start": 2077.29,
"duration": 2.97
},
{
"text": "of tricky syntax to wrap your mind",
"start": 2078.85,
"duration": 2.4
},
{
"text": "around if you've never seen it before",
"start": 2080.26,
"duration": 2.85
},
{
"text": "but the big-picture way to think of it",
"start": 2081.25,
"duration": 3.9
},
{
"text": "is add event listener takes two",
"start": 2083.11,
"duration": 4.44
},
{
"text": "arguments one is the event the second is",
"start": 2085.15,
"duration": 4.53
},
{
"text": "the function so here first is the event",
"start": 2087.55,
"duration": 4.2
},
{
"text": "Dom content loaded and the second",
"start": 2089.68,
"duration": 4.8
},
{
"text": "argument is a function and I declare the",
"start": 2091.75,
"duration": 4.11
},
{
"text": "function same as before just using",
"start": 2094.48,
"duration": 3.3
},
{
"text": "function I haven't given the function a",
"start": 2095.86,
"duration": 4.05
},
{
"text": "name because strictly speaking it",
"start": 2097.78,
"duration": 3.18
},
{
"text": "doesn't need a name",
"start": 2099.91,
"duration": 2.31
},
{
"text": "I'm never going to refer to this",
"start": 2100.96,
"duration": 3.12
},
{
"text": "function by name so it is what we might",
"start": 2102.22,
"duration": 3.99
},
{
"text": "call an anonymous function a function",
"start": 2104.08,
"duration": 4.71
},
{
"text": "that has no name but I'm still passing",
"start": 2106.21,
"duration": 4.32
},
{
"text": "it into the add event listener function",
"start": 2108.79,
"duration": 4.47
},
{
"text": "as an argument because I want to run the",
"start": 2110.53,
"duration": 4.89
},
{
"text": "code inside of the function once the Dom",
"start": 2113.26,
"duration": 4.38
},
{
"text": "is done loading and so inside of curly",
"start": 2115.42,
"duration": 4.17
},
{
"text": "braces then is the content of that",
"start": 2117.64,
"duration": 3.81
},
{
"text": "function the content of what code should",
"start": 2119.59,
"duration": 3.75
},
{
"text": "run when the Dom is done loading and",
"start": 2121.45,
"duration": 3.81
},
{
"text": "then at the end I again used just this",
"start": 2123.34,
"duration": 3.84
},
{
"text": "end parenthesis where that end",
"start": 2125.26,
"duration": 3.54
},
{
"text": "parenthesis lines up with this",
"start": 2127.18,
"duration": 4.17
},
{
"text": "parenthesis here this is enclosing all",
"start": 2128.8,
"duration": 5.07
},
{
"text": "of the arguments to add event listener",
"start": 2131.35,
"duration": 3.96
},
{
"text": "where the first one is Dom content",
"start": 2133.87,
"duration": 3.9
},
{
"text": "loaded and the second one is this entire",
"start": 2135.31,
"duration": 4.86
},
{
"text": "function that might span multiple lines",
"start": 2137.77,
"duration": 4.35
},
{
"text": "so you'll see syntax like this quite a",
"start": 2140.17,
"duration": 5.1
},
{
"text": "bit in JavaScript but now what I want to",
"start": 2142.12,
"duration": 5.28
},
{
"text": "do is adding the event listener to the",
"start": 2145.27,
"duration": 4.32
},
{
"text": "button I can go ahead and just for place",
"start": 2147.4,
"duration": 4.77
},
{
"text": "and put it here and it turns out that if",
"start": 2149.59,
"duration": 3.15
},
{
"text": "I wanted to",
"start": 2152.17,
"duration": 2.37
},
{
"text": "instead of saying dot on click equals",
"start": 2152.74,
"duration": 2.97
},
{
"text": "count you could",
"start": 2154.54,
"duration": 2.579
},
{
"text": "used the same syntax of add",
"start": 2155.71,
"duration": 2.67
},
{
"text": "eventlistener I could say at",
"start": 2157.119,
"duration": 5.071
},
{
"text": "eventlistener click and then count to",
"start": 2158.38,
"duration": 6.57
},
{
"text": "mean when the click event happens go",
"start": 2162.19,
"duration": 4.5
},
{
"text": "ahead and run the count function but you",
"start": 2164.95,
"duration": 3.45
},
{
"text": "can equivalently shorthand this and just",
"start": 2166.69,
"duration": 4.35
},
{
"text": "say dot on click equals count and that",
"start": 2168.4,
"duration": 5.25
},
{
"text": "would work just as well so now what",
"start": 2171.04,
"duration": 4.799
},
{
"text": "we're saying here is that wait until the",
"start": 2173.65,
"duration": 3.75
},
{
"text": "Dom has done loaded wait until all the",
"start": 2175.839,
"duration": 3.811
},
{
"text": "content on the page is loaded and then",
"start": 2177.4,
"duration": 4.29
},
{
"text": "go ahead and run this function and what",
"start": 2179.65,
"duration": 3.719
},
{
"text": "the function is going to do is it's",
"start": 2181.69,
"duration": 3.75
},
{
"text": "going to add the event handler to this",
"start": 2183.369,
"duration": 4.171
},
{
"text": "button and that'll work because now",
"start": 2185.44,
"duration": 3.929
},
{
"text": "we'll be able to find the button because",
"start": 2187.54,
"duration": 3.87
},
{
"text": "now all of the content of the Dom has",
"start": 2189.369,
"duration": 5.191
},
{
"text": "loaded so now if I go back Refresh",
"start": 2191.41,
"duration": 5.25
},
{
"text": "counter dot HTML you'll notice that the",
"start": 2194.56,
"duration": 4.049
},
{
"text": "JavaScript error goes away I don't seem",
"start": 2196.66,
"duration": 4.53
},
{
"text": "to have that error anymore and now if I",
"start": 2198.609,
"duration": 4.411
},
{
"text": "press count were able to see the count",
"start": 2201.19,
"duration": 5.55
},
{
"text": "increment just as before as well and so",
"start": 2203.02,
"duration": 5.849
},
{
"text": "this then is an improvement upon what",
"start": 2206.74,
"duration": 4.16
},
{
"text": "I've had before where now I'm able to",
"start": 2208.869,
"duration": 5.041
},
{
"text": "separate out my JavaScript code from all",
"start": 2210.9,
"duration": 5.469
},
{
"text": "of the rest of my code as well but much",
"start": 2213.91,
"duration": 4.74
},
{
"text": "as in the case of CSS where we were able",
"start": 2216.369,
"duration": 4.021
},
{
"text": "to take CSS that was originally located",
"start": 2218.65,
"duration": 3.78
},
{
"text": "in the head of our page and move it into",
"start": 2220.39,
"duration": 3.719
},
{
"text": "a separate file you can do the same",
"start": 2222.43,
"duration": 3.3
},
{
"text": "thing with JavaScript too and this can",
"start": 2224.109,
"duration": 3.031
},
{
"text": "be helpful if you have multiple people",
"start": 2225.73,
"duration": 3.03
},
{
"text": "working on different files you want one",
"start": 2227.14,
"duration": 3.66
},
{
"text": "person working on the HTML and someone",
"start": 2228.76,
"duration": 4.109
},
{
"text": "else working on the JavaScript it can be",
"start": 2230.8,
"duration": 4.2
},
{
"text": "helpful if you expect that one of these",
"start": 2232.869,
"duration": 3.331
},
{
"text": "things is going to change more",
"start": 2235.0,
"duration": 2.52
},
{
"text": "frequently than the other so you might",
"start": 2236.2,
"duration": 3.0
},
{
"text": "not need to load the other one as often",
"start": 2237.52,
"duration": 3.96
},
{
"text": "so there can be value in separating our",
"start": 2239.2,
"duration": 4.59
},
{
"text": "HTML code from our JavaScript even more",
"start": 2241.48,
"duration": 4.35
},
{
"text": "and by moving our JavaScript into a",
"start": 2243.79,
"duration": 4.23
},
{
"text": "separate file and so in order to do that",
"start": 2245.83,
"duration": 5.279
},
{
"text": "I can create a new file that I'll just",
"start": 2248.02,
"duration": 5.91
},
{
"text": "call counter j/s which will contain all",
"start": 2251.109,
"duration": 6.061
},
{
"text": "of the JavaScript for my counter HTML",
"start": 2253.93,
"duration": 6.03
},
{
"text": "file so in order to do that what I can",
"start": 2257.17,
"duration": 5.22
},
{
"text": "say is let's go ahead and copy all of",
"start": 2259.96,
"duration": 4.83
},
{
"text": "this JavaScript code go ahead and cut it",
"start": 2262.39,
"duration": 4.469
},
{
"text": "out of this page and I'll paste it into",
"start": 2264.79,
"duration": 3.9
},
{
"text": "counter j/s remove some of that",
"start": 2266.859,
"duration": 6.151
},
{
"text": "indentation so now I have a file called",
"start": 2268.69,
"duration": 6.63
},
{
"text": "counter das that just contains all of",
"start": 2273.01,
"duration": 4.68
},
{
"text": "the JavaScript I want to run on my",
"start": 2275.32,
"duration": 6.42
},
{
"text": "counter dot HTML page and now rather",
"start": 2277.69,
"duration": 5.82
},
{
"text": "than include actual JavaScript in",
"start": 2281.74,
"duration": 4.65
},
{
"text": "between these script tags what I can say",
"start": 2283.51,
"duration": 6.599
},
{
"text": "is script SRC SRC first",
"start": 2286.39,
"duration": 8.31
},
{
"text": "equals a counter Jas for example if I go",
"start": 2290.109,
"duration": 7.47
},
{
"text": "ahead and reference counter Jas and use",
"start": 2294.7,
"duration": 5.49
},
{
"text": "that JavaScript in the head of the page",
"start": 2297.579,
"duration": 4.47
},
{
"text": "here and that then is going to work",
"start": 2300.19,
"duration": 3.72
},
{
"text": "exactly in the same way I still am able",
"start": 2302.049,
"duration": 3.78
},
{
"text": "to count as high as I'd like I still get",
"start": 2303.91,
"duration": 3.24
},
{
"text": "an alert every time the count reaches a",
"start": 2305.829,
"duration": 3.601
},
{
"text": "multiple of ten but my HTML is now a",
"start": 2307.15,
"duration": 3.929
},
{
"text": "little bit simpler it's just the body",
"start": 2309.43,
"duration": 3.75
},
{
"text": "it's just the h1 in the button and then",
"start": 2311.079,
"duration": 5.191
},
{
"text": "all of my javascript is now located in a",
"start": 2313.18,
"duration": 5.82
},
{
"text": "separate file that allows me to do that",
"start": 2316.27,
"duration": 5.01
},
{
"text": "allows me to keep my HTML code and my",
"start": 2319.0,
"duration": 3.599
},
{
"text": "JavaScript code separate from each other",
"start": 2321.28,
"duration": 3.24
},
{
"text": "and that can be value for valuable for a",
"start": 2322.599,
"duration": 4.081
},
{
"text": "couple of reasons among them if I have",
"start": 2324.52,
"duration": 4.68
},
{
"text": "common JavaScript code that's in use by",
"start": 2326.68,
"duration": 5.04
},
{
"text": "multiple different HTML pages multiple",
"start": 2329.2,
"duration": 4.68
},
{
"text": "HTML pages can all include the same",
"start": 2331.72,
"duration": 4.23
},
{
"text": "JavaScript source rather than needing to",
"start": 2333.88,
"duration": 2.76
},
{
"text": "repeat myself",
"start": 2335.95,
"duration": 2.669
},
{
"text": "use the same JavaScript across multiple",
"start": 2336.64,
"duration": 4.02
},
{
"text": "different pages I can just use the same",
"start": 2338.619,
"duration": 3.841
},
{
"text": "JavaScript across all of them and",
"start": 2340.66,
"duration": 3.78
},
{
"text": "that'll be helpful too as we begin to",
"start": 2342.46,
"duration": 3.45
},
{
"text": "take a look later at some JavaScript",
"start": 2344.44,
"duration": 3.27
},
{
"text": "libraries which are JavaScript written",
"start": 2345.91,
"duration": 4.05
},
{
"text": "by other people we can just include",
"start": 2347.71,
"duration": 4.109
},
{
"text": "other people's JavaScript in our own",
"start": 2349.96,
"duration": 4.349
},
{
"text": "webpages just by adding a script tag at",
"start": 2351.819,
"duration": 4.23
},
{
"text": "the top of our page that specifies a",
"start": 2354.309,
"duration": 3.181
},
{
"text": "particular source you may have already",
"start": 2356.049,
"duration": 3.601
},
{
"text": "interacted with bootstrap that has its",
"start": 2357.49,
"duration": 4.17
},
{
"text": "own JavaScript code and you can include",
"start": 2359.65,
"duration": 4.139
},
{
"text": "bootstraps JavaScript just by including",
"start": 2361.66,
"duration": 4.86
},
{
"text": "a script tag at the top of our HTML page",
"start": 2363.789,
"duration": 5.131
},
{
"text": "in order to say go ahead and include all",
"start": 2366.52,
"duration": 6.23
},
{
"text": "of that javascript in our page as well",
"start": 2368.92,
"duration": 6.51
},
{
"text": "so what else can we do now now that we",
"start": 2372.75,
"duration": 4.539
},
{
"text": "have the ability to like get at elements",
"start": 2375.43,
"duration": 3.84
},
{
"text": "of the Dom and actually manipulate their",
"start": 2377.289,
"duration": 4.141
},
{
"text": "contents well one thing we can do is",
"start": 2379.27,
"duration": 4.47
},
{
"text": "begin to make our pages a little bit",
"start": 2381.43,
"duration": 3.929
},
{
"text": "more interactive actually respond to",
"start": 2383.74,
"duration": 4.049
},
{
"text": "what users are doing on the page whether",
"start": 2385.359,
"duration": 4.68
},
{
"text": "the user is typing something in or maybe",
"start": 2387.789,
"duration": 4.381
},
{
"text": "filling out a form for example so let's",
"start": 2390.039,
"duration": 3.721
},
{
"text": "go ahead and try an example of that",
"start": 2392.17,
"duration": 3.09
},
{
"text": "where the user might be filling out a",
"start": 2393.76,
"duration": 3.51
},
{
"text": "form and we would like for our code to",
"start": 2395.26,
"duration": 4.109
},
{
"text": "somehow respond to what it is that they",
"start": 2397.27,
"duration": 4.11
},
{
"text": "type I'll go ahead and go back into",
"start": 2399.369,
"duration": 6.42
},
{
"text": "hello dot HTML and now inside of the",
"start": 2401.38,
"duration": 6.479
},
{
"text": "body of the page I've said hello at the",
"start": 2405.789,
"duration": 3.99
},
{
"text": "top I'm here instead of a button I'm",
"start": 2407.859,
"duration": 5.46
},
{
"text": "going to have a form this HTML form will",
"start": 2409.779,
"duration": 4.83
},
{
"text": "look like the HTML forms we've seen",
"start": 2413.319,
"duration": 3.871
},
{
"text": "before a have an input field that'll add",
"start": 2414.609,
"duration": 4.531
},
{
"text": "the auto focus attribute to to mean like",
"start": 2417.19,
"duration": 3.24
},
{
"text": "automatically focus this input field",
"start": 2419.14,
"duration": 3.179
},
{
"text": "when I open the page because I might",
"start": 2420.43,
"duration": 2.189
},
{
"text": "want",
"start": 2422.319,
"duration": 2.911
},
{
"text": "user to start typing right away I'm",
"start": 2422.619,
"duration": 4.67
},
{
"text": "gonna give this input field an ID of",
"start": 2425.23,
"duration": 5.789
},
{
"text": "name for example and then a placeholder",
"start": 2427.289,
"duration": 9.641
},
{
"text": "of name capital n whose type is text so",
"start": 2431.019,
"duration": 7.201
},
{
"text": "what have I done here I've created an",
"start": 2436.93,
"duration": 2.76
},
{
"text": "input field where the user can type in",
"start": 2438.22,
"duration": 3.51
},
{
"text": "some text the placeholder the thing the",
"start": 2439.69,
"duration": 4.02
},
{
"text": "user see is filled into that input field",
"start": 2441.73,
"duration": 4.26
},
{
"text": "originally will just be capital and name",
"start": 2443.71,
"duration": 3.69
},
{
"text": "telling them they should type their name",
"start": 2445.99,
"duration": 3.869
},
{
"text": "in here and I've given this input field",
"start": 2447.4,
"duration": 6.09
},
{
"text": "an ID some unique identifier such that I",
"start": 2449.859,
"duration": 6.361
},
{
"text": "later on can reference and find this",
"start": 2453.49,
"duration": 5.67
},
{
"text": "particular input field and then I have",
"start": 2456.22,
"duration": 5.97
},
{
"text": "input type equals submit some way for me",
"start": 2459.16,
"duration": 7.439
},
{
"text": "to now submit this form as well and so",
"start": 2462.19,
"duration": 7.579
},
{
"text": "if I load this page load hello dot HTML",
"start": 2466.599,
"duration": 6.27
},
{
"text": "here's what I see hello a field where I",
"start": 2469.769,
"duration": 4.75
},
{
"text": "can type in my name the placeholder name",
"start": 2472.869,
"duration": 3.301
},
{
"text": "shows up there for me and then a button",
"start": 2474.519,
"duration": 5.52
},
{
"text": "where I can submit this form and now",
"start": 2476.17,
"duration": 5.55
},
{
"text": "what I'd like to do inside of my",
"start": 2480.039,
"duration": 3.75
},
{
"text": "JavaScript is instead of this hello",
"start": 2481.72,
"duration": 3.779
},
{
"text": "function what I'm going to do is I'm",
"start": 2483.789,
"duration": 4.23
},
{
"text": "going to first run some JavaScript when",
"start": 2485.499,
"duration": 4.171
},
{
"text": "the Dom is done loading and so I'll use",
"start": 2488.019,
"duration": 2.941
},
{
"text": "that same line from before you're gonna",
"start": 2489.67,
"duration": 2.97
},
{
"text": "see it quite a bit we're gonna say",
"start": 2490.96,
"duration": 4.529
},
{
"text": "document add event listener Dom content",
"start": 2492.64,
"duration": 5.669
},
{
"text": "loaded and then this function to mean go",
"start": 2495.489,
"duration": 4.86
},
{
"text": "ahead and run this code when the Dom is",
"start": 2498.309,
"duration": 4.171
},
{
"text": "done loaded and the code I'd like to run",
"start": 2500.349,
"duration": 6.69
},
{
"text": "is to say when I submit the form I want",
"start": 2502.48,
"duration": 6.089
},
{
"text": "something to happen when I submit the",
"start": 2507.039,
"duration": 3.06
},
{
"text": "form maybe I want to display an alert",
"start": 2508.569,
"duration": 3.601
},
{
"text": "that if I type in Brian it'll say hello",
"start": 2510.099,
"duration": 3.541
},
{
"text": "Brian or if I typed in David it'll say",
"start": 2512.17,
"duration": 3.72
},
{
"text": "hello David for example so how many I do",
"start": 2513.64,
"duration": 4.74
},
{
"text": "that well how do I get the form that's",
"start": 2515.89,
"duration": 3.99
},
{
"text": "the first question anytime you want to",
"start": 2518.38,
"duration": 3.659
},
{
"text": "get at an element one particular element",
"start": 2519.88,
"duration": 4.619
},
{
"text": "on an HTML page usually what we're going",
"start": 2522.039,
"duration": 5.641
},
{
"text": "to do is document dot query selector to",
"start": 2524.499,
"duration": 5.55
},
{
"text": "say get me the element that is a form",
"start": 2527.68,
"duration": 3.99
},
{
"text": "and there's only one form on the page so",
"start": 2530.049,
"duration": 3.06
},
{
"text": "I don't have to worry about ambiguity",
"start": 2531.67,
"duration": 3.56
},
{
"text": "I'm just saying get me that form and",
"start": 2533.109,
"duration": 6.24
},
{
"text": "then I can say dot on submit when you",
"start": 2535.23,
"duration": 6.849
},
{
"text": "submit the form what code should run and",
"start": 2539.349,
"duration": 4.561
},
{
"text": "if I had a name of a function like a",
"start": 2542.079,
"duration": 4.051
},
{
"text": "function f I could just say like run",
"start": 2543.91,
"duration": 4.369
},
{
"text": "function f when the form is submitted",
"start": 2546.13,
"duration": 5.28
},
{
"text": "but alternatively just as before instead",
"start": 2548.279,
"duration": 4.631
},
{
"text": "of providing the name of a function I",
"start": 2551.41,
"duration": 3.57
},
{
"text": "can also just provide the function",
"start": 2552.91,
"duration": 2.84
},
{
"text": "itself",
"start": 2554.98,
"duration": 4.01
},
{
"text": "I can say function and then in between",
"start": 2555.75,
"duration": 6.39
},
{
"text": "these curly braces I can specify exactly",
"start": 2558.99,
"duration": 5.82
},
{
"text": "what code should run when the form is",
"start": 2562.14,
"duration": 4.41
},
{
"text": "submitted by providing this anonymous",
"start": 2564.81,
"duration": 4.08
},
{
"text": "function instead using this anonymous",
"start": 2566.55,
"duration": 5.28
},
{
"text": "function as the value of the on submit",
"start": 2568.89,
"duration": 5.94
},
{
"text": "property of this form and so now what",
"start": 2571.83,
"duration": 5.1
},
{
"text": "I'd like to do is somehow get access to",
"start": 2574.83,
"duration": 4.35
},
{
"text": "whatever the user typed into the input",
"start": 2576.93,
"duration": 4.29
},
{
"text": "field whatever the user's name happens",
"start": 2579.18,
"duration": 4.14
},
{
"text": "to be and so I could get the input field",
"start": 2581.22,
"duration": 5.49
},
{
"text": "by a document dot query selector input",
"start": 2583.32,
"duration": 5.88
},
{
"text": "and that would work this time but we'll",
"start": 2586.71,
"duration": 3.81
},
{
"text": "want to start to be a little bit careful",
"start": 2589.2,
"duration": 2.97
},
{
"text": "because on this page there are multiple",
"start": 2590.52,
"duration": 3.18
},
{
"text": "different input elements as an input",
"start": 2592.17,
"duration": 3.54
},
{
"text": "element here for typing in the name and",
"start": 2593.7,
"duration": 5.16
},
{
"text": "a second input element here for telling",
"start": 2595.71,
"duration": 4.86
},
{
"text": "me giving me a button where I can submit",
"start": 2598.86,
"duration": 4.08
},
{
"text": "this particular HTML form and so what I",
"start": 2600.57,
"duration": 4.5
},
{
"text": "probably want to do is be a little bit",
"start": 2602.94,
"duration": 4.44
},
{
"text": "more specific and it turns out that",
"start": 2605.07,
"duration": 4.41
},
{
"text": "inside of query selector I can use all",
"start": 2607.38,
"duration": 4.53
},
{
"text": "of the standard ways in CSS that we",
"start": 2609.48,
"duration": 5.04
},
{
"text": "could select for a particular element so",
"start": 2611.91,
"duration": 5.01
},
{
"text": "in CSS if you'll recall we had the",
"start": 2614.52,
"duration": 4.8
},
{
"text": "ability to run CSS and just say style",
"start": 2616.92,
"duration": 4.95
},
{
"text": "all the h1 or we could say style all the",
"start": 2619.32,
"duration": 4.29
},
{
"text": "things with this particular ID or with",
"start": 2621.87,
"duration": 3.93
},
{
"text": "this particular class and document our",
"start": 2623.61,
"duration": 4.2
},
{
"text": "query selector works the same way that I",
"start": 2625.8,
"duration": 4.41
},
{
"text": "can say document query selector and pass",
"start": 2627.81,
"duration": 5.31
},
{
"text": "in a tag to say like get me the h1",
"start": 2630.21,
"duration": 4.8
},
{
"text": "element or get me the button or get me",
"start": 2633.12,
"duration": 3.99
},
{
"text": "the form but if there are multiple h1",
"start": 2635.01,
"duration": 3.54
},
{
"text": "elements are multiple buttons and",
"start": 2637.11,
"duration": 3.21
},
{
"text": "multiple forms I can be more specific",
"start": 2638.55,
"duration": 2.28
},
{
"text": "than that",
"start": 2640.32,
"duration": 3.9
},
{
"text": "if for example an element has an ID in",
"start": 2640.83,
"duration": 5.43
},
{
"text": "which case I can say document query",
"start": 2644.22,
"duration": 4.56
},
{
"text": "selector and then in quotation marks the",
"start": 2646.26,
"duration": 5.34
},
{
"text": "hash mark and then the name of the ID to",
"start": 2648.78,
"duration": 4.35
},
{
"text": "say get me the element with that",
"start": 2651.6,
"duration": 3.75
},
{
"text": "particular ID again using the exact same",
"start": 2653.13,
"duration": 5.4
},
{
"text": "syntax that CSS uses if I want to apply",
"start": 2655.35,
"duration": 5.64
},
{
"text": "a particular set of styles to only one",
"start": 2658.53,
"duration": 5.64
},
{
"text": "element that only has one ID likewise",
"start": 2660.99,
"duration": 5.49
},
{
"text": "two I can say document query selector",
"start": 2664.17,
"duration": 4.92
},
{
"text": "and then use dot followed by the name of",
"start": 2666.48,
"duration": 4.41
},
{
"text": "a class if there's a particular",
"start": 2669.09,
"duration": 3.93
},
{
"text": "particular class of elements and I want",
"start": 2670.89,
"duration": 4.5
},
{
"text": "to just get one of those and to say get",
"start": 2673.02,
"duration": 4.53
},
{
"text": "me an element that has this particular",
"start": 2675.39,
"duration": 4.5
},
{
"text": "class in order to manipulate it as well",
"start": 2677.55,
"duration": 4.23
},
{
"text": "so the same types of syntax that we",
"start": 2679.89,
"duration": 4.23
},
{
"text": "could use in CSS for trying to reference",
"start": 2681.78,
"duration": 5.22
},
{
"text": "and get at a particular HTML element we",
"start": 2684.12,
"duration": 4.86
},
{
"text": "can do the same thing here with document",
"start": 2687.0,
"duration": 2.64
},
{
"text": "query so",
"start": 2688.98,
"duration": 3.72
},
{
"text": "to go ahead and try and get a particular",
"start": 2689.64,
"duration": 5.07
},
{
"text": "element based on its tag name based on",
"start": 2692.7,
"duration": 4.5
},
{
"text": "this ID or based on its class and it was",
"start": 2694.71,
"duration": 4.44
},
{
"text": "for that reason that inside of the HTML",
"start": 2697.2,
"duration": 5.7
},
{
"text": "page for my input I gave the input an",
"start": 2699.15,
"duration": 6.719
},
{
"text": "idea of name I wanted some way to be",
"start": 2702.9,
"duration": 5.219
},
{
"text": "able to uniquely reference it and I can",
"start": 2705.869,
"duration": 4.531
},
{
"text": "uniquely reference it not by input but",
"start": 2708.119,
"duration": 5.341
},
{
"text": "by pound name where I can say get me the",
"start": 2710.4,
"duration": 6.24
},
{
"text": "element that has an ID of name and that",
"start": 2713.46,
"duration": 4.409
},
{
"text": "is the element that I would like to",
"start": 2716.64,
"duration": 3.619
},
{
"text": "extract inside of my JavaScript code",
"start": 2717.869,
"duration": 5.041
},
{
"text": "once I have that HTML element what I",
"start": 2720.259,
"duration": 4.121
},
{
"text": "want is like what the user actually",
"start": 2722.91,
"duration": 4.109
},
{
"text": "typed into that input field and it turns",
"start": 2724.38,
"duration": 4.05
},
{
"text": "out that if you have an input field in",
"start": 2727.019,
"duration": 3.72
},
{
"text": "HTML I can get access to what the user",
"start": 2728.43,
"duration": 5.129
},
{
"text": "typed in by accessing its value property",
"start": 2730.739,
"duration": 4.921
},
{
"text": "value is a property that fur that refers",
"start": 2733.559,
"duration": 4.351
},
{
"text": "to what it is the user actually typed in",
"start": 2735.66,
"duration": 6.389
},
{
"text": "so I can say dot value and I'm going to",
"start": 2737.91,
"duration": 5.669
},
{
"text": "go ahead and save that inside of a",
"start": 2742.049,
"duration": 3.121
},
{
"text": "variable so I could say something like",
"start": 2743.579,
"duration": 4.2
},
{
"text": "let name equal whatever the user typed",
"start": 2745.17,
"duration": 4.8
},
{
"text": "in but if I'm not going to reassign name",
"start": 2747.779,
"duration": 3.691
},
{
"text": "to something else inside of this",
"start": 2749.97,
"duration": 3.149
},
{
"text": "function inside of this function I'm",
"start": 2751.47,
"duration": 3.149
},
{
"text": "really going to get the name once and",
"start": 2753.119,
"duration": 2.94
},
{
"text": "I'm not gonna change it inside of the",
"start": 2754.619,
"duration": 3.9
},
{
"text": "function so I can use a constable",
"start": 2756.059,
"duration": 4.171
},
{
"text": "instead that would be better designed to",
"start": 2758.519,
"duration": 3.51
},
{
"text": "say I have a constant variable called",
"start": 2760.23,
"duration": 3.9
},
{
"text": "name which is equal to document query",
"start": 2762.029,
"duration": 4.171
},
{
"text": "selector get me the element whose ideas",
"start": 2764.13,
"duration": 5.879
},
{
"text": "name and get access to its value and now",
"start": 2766.2,
"duration": 5.849
},
{
"text": "I can display an alert I can alert",
"start": 2770.009,
"duration": 5.911
},
{
"text": "something like in backticks hello comma",
"start": 2772.049,
"duration": 6.48
},
{
"text": "and then using the dollar sign curly",
"start": 2775.92,
"duration": 4.5
},
{
"text": "brace syntax I can say plug in the name",
"start": 2778.529,
"duration": 4.851
},
{
"text": "there followed by an exclamation point",
"start": 2780.42,
"duration": 5.49
},
{
"text": "so I've extracted the name from the form",
"start": 2783.38,
"duration": 4.389
},
{
"text": "get me the input field where they type",
"start": 2785.91,
"duration": 3.839
},
{
"text": "to the name get access to its value and",
"start": 2787.769,
"duration": 4.32
},
{
"text": "then I'm displaying an alert that is",
"start": 2789.749,
"duration": 5.401
},
{
"text": "going to say hello to that person for",
"start": 2792.089,
"duration": 7.71
},
{
"text": "example and so now for refresh the page",
"start": 2795.15,
"duration": 8.04
},
{
"text": "I type in my name I press submit I get",
"start": 2799.799,
"duration": 4.891
},
{
"text": "an alert that says hello Brian",
"start": 2803.19,
"duration": 4.859
},
{
"text": "press ok I can try it again I can type",
"start": 2804.69,
"duration": 5.099
},
{
"text": "in something like David it press submit",
"start": 2808.049,
"duration": 4.55
},
{
"text": "and now the page says hello David",
"start": 2809.789,
"duration": 5.101
},
{
"text": "so here again we've been able to combine",
"start": 2812.599,
"duration": 4.99
},
{
"text": "event listeners and functions and query",
"start": 2814.89,
"duration": 5.31
},
{
"text": "selector to be able to both read",
"start": 2817.589,
"duration": 4.351
},
{
"text": "information from the page in order to",
"start": 2820.2,
"duration": 2.76
},
{
"text": "say get me",
"start": 2821.94,
"duration": 3.36
},
{
"text": "this particular HTML element find me an",
"start": 2822.96,
"duration": 4.71
},
{
"text": "HTML element and access like what the",
"start": 2825.3,
"duration": 4.02
},
{
"text": "user typed into it the dot value",
"start": 2827.67,
"duration": 3.39
},
{
"text": "property that gets me what the user",
"start": 2829.32,
"duration": 3.69
},
{
"text": "typed into an input field and we've been",
"start": 2831.06,
"duration": 3.57
},
{
"text": "able to combine that with event",
"start": 2833.01,
"duration": 3.09
},
{
"text": "listeners and alerts that are able to",
"start": 2834.63,
"duration": 4.14
},
{
"text": "actually respond dynamically to when a",
"start": 2836.1,
"duration": 4.5
},
{
"text": "user submits the form or when the entire",
"start": 2838.77,
"duration": 3.99
},
{
"text": "content of the page is done loading in",
"start": 2840.6,
"duration": 3.66
},
{
"text": "order to produce some interesting",
"start": 2842.76,
"duration": 4.8
},
{
"text": "effects as well but it turns out we can",
"start": 2844.26,
"duration": 6.03
},
{
"text": "do more than just change like the HTML",
"start": 2847.56,
"duration": 4.98
},
{
"text": "that is contained within an element we",
"start": 2850.29,
"duration": 4.74
},
{
"text": "can also change CSS as well change the",
"start": 2852.54,
"duration": 4.62
},
{
"text": "style properties of a particular element",
"start": 2855.03,
"duration": 4.62
},
{
"text": "as well so let's go ahead and see an",
"start": 2857.16,
"duration": 4.89
},
{
"text": "example of that I'll go ahead and create",
"start": 2859.65,
"duration": 5.25
},
{
"text": "a new file then I'll call colors HTML",
"start": 2862.05,
"duration": 4.92
},
{
"text": "and inside of colors I'll include the",
"start": 2864.9,
"duration": 5.88
},
{
"text": "same standard HTML boilerplate code that",
"start": 2866.97,
"duration": 5.34
},
{
"text": "we often start with a head section with",
"start": 2870.78,
"duration": 4.71
},
{
"text": "a title and a body section and inside of",
"start": 2872.31,
"duration": 5.4
},
{
"text": "the body of this page I'm going to",
"start": 2875.49,
"duration": 5.58
},
{
"text": "display a heading that just says hello",
"start": 2877.71,
"duration": 5.61
},
{
"text": "for example and maybe I'll give it an ID",
"start": 2881.07,
"duration": 4.38
},
{
"text": "just so I can reference it by name maybe",
"start": 2883.32,
"duration": 5.34
},
{
"text": "it has an ID of hello and then I'll have",
"start": 2885.45,
"duration": 6.15
},
{
"text": "three buttons I'll have a button called",
"start": 2888.66,
"duration": 6.54
},
{
"text": "read a button called blue and then a",
"start": 2891.6,
"duration": 7.11
},
{
"text": "button called green for example where",
"start": 2895.2,
"duration": 7.14
},
{
"text": "now if I open up colors dot HTML here's",
"start": 2898.71,
"duration": 5.76
},
{
"text": "what I see I see a big heading that says",
"start": 2902.34,
"duration": 4.2
},
{
"text": "hello and then I see three buttons red",
"start": 2904.47,
"duration": 3.48
},
{
"text": "blue and green but of course right now",
"start": 2906.54,
"duration": 3.9
},
{
"text": "these buttons don't actually do anything",
"start": 2907.95,
"duration": 4.5
},
{
"text": "how do I get the buttons to do something",
"start": 2910.44,
"duration": 4.02
},
{
"text": "well that's where JavaScript's going to",
"start": 2912.45,
"duration": 3.99
},
{
"text": "come in I'll add a script tag to the top",
"start": 2914.46,
"duration": 4.35
},
{
"text": "of my page and I only want to run this",
"start": 2916.44,
"duration": 4.05
},
{
"text": "JavaScript when the Dom is done loading",
"start": 2918.81,
"duration": 3.87
},
{
"text": "so again we'll use the same syntax as",
"start": 2920.49,
"duration": 5.42
},
{
"text": "before document dot add eventlistener",
"start": 2922.68,
"duration": 7.14
},
{
"text": "Dom content loaded and then run this",
"start": 2925.91,
"duration": 6.1
},
{
"text": "function to say everything in between",
"start": 2929.82,
"duration": 4.44
},
{
"text": "these curly braces this is all the code",
"start": 2932.01,
"duration": 4.05
},
{
"text": "that should run once the page is done",
"start": 2934.26,
"duration": 3.81
},
{
"text": "loading and what I'd really like to do",
"start": 2936.06,
"duration": 4.2
},
{
"text": "is get at these three buttons and say",
"start": 2938.07,
"duration": 3.48
},
{
"text": "when you click on each one of them do",
"start": 2940.26,
"duration": 2.55
},
{
"text": "something different like change the",
"start": 2941.55,
"duration": 3.93
},
{
"text": "color of a particular HTML element and",
"start": 2942.81,
"duration": 4.29
},
{
"text": "in order to do that I need some way of",
"start": 2945.48,
"duration": 3.63
},
{
"text": "uniquely referencing these buttons so to",
"start": 2947.1,
"duration": 3.18
},
{
"text": "do that I'm going to give them all IDs",
"start": 2949.11,
"duration": 3.78
},
{
"text": "this button will have an ID of red this",
"start": 2950.28,
"duration": 4.59
},
{
"text": "button will have an ID of blue this",
"start": 2952.89,
"duration": 3.69
},
{
"text": "button will have an ID of green",
"start": 2954.87,
"duration": 3.45
},
{
"text": "unique names I can give to the buttons",
"start": 2956.58,
"duration": 4.17
},
{
"text": "in HTML such that in JavaScript",
"start": 2958.32,
"duration": 5.97
},
{
"text": "I'm later able to reference them so what",
"start": 2960.75,
"duration": 5.64
},
{
"text": "I what do I include now here inside of",
"start": 2964.29,
"duration": 3.18
},
{
"text": "my JavaScript code",
"start": 2966.39,
"duration": 4.5
},
{
"text": "well let me say document dot query",
"start": 2967.47,
"duration": 8.13
},
{
"text": "selector hash read to say get me the",
"start": 2970.89,
"duration": 8.4
},
{
"text": "element whose ID is read and when you're",
"start": 2975.6,
"duration": 6.27
},
{
"text": "clicked on on click go ahead and run",
"start": 2979.29,
"duration": 4.14
},
{
"text": "this function",
"start": 2981.87,
"duration": 3.63
},
{
"text": "what should the function do well I want",
"start": 2983.43,
"duration": 4.59
},
{
"text": "to take this h1 element and change its",
"start": 2985.5,
"duration": 5.04
},
{
"text": "color to red I want to change the font",
"start": 2988.02,
"duration": 4.62
},
{
"text": "color to red and I'll leave a comment to",
"start": 2990.54,
"duration": 3.9
},
{
"text": "myself in JavaScript the way you can",
"start": 2992.64,
"duration": 3.21
},
{
"text": "leave a comment just a document what",
"start": 2994.44,
"duration": 3.24
},
{
"text": "you're doing is using these two slashes",
"start": 2995.85,
"duration": 3.78
},
{
"text": "the two slashes indicate everything",
"start": 2997.68,
"duration": 3.66
},
{
"text": "after that on the page is going to be a",
"start": 2999.63,
"duration": 3.78
},
{
"text": "comment browser will ignore it but it",
"start": 3001.34,
"duration": 3.78
},
{
"text": "can be useful to use a programmer and to",
"start": 3003.41,
"duration": 3.18
},
{
"text": "someone who's reading your code to be",
"start": 3005.12,
"duration": 3.03
},
{
"text": "able to see what it is that you're",
"start": 3006.59,
"duration": 4.29
},
{
"text": "describing here on the page and now what",
"start": 3008.15,
"duration": 5.25
},
{
"text": "I'd like to do is document query",
"start": 3010.88,
"duration": 6.39
},
{
"text": "selector hello get me the HTML element",
"start": 3013.4,
"duration": 6.39
},
{
"text": "whose ID is hello and go ahead and",
"start": 3017.27,
"duration": 6.24
},
{
"text": "modify its style property and now inside",
"start": 3019.79,
"duration": 6.27
},
{
"text": "of this style object I can modify any of",
"start": 3023.51,
"duration": 4.68
},
{
"text": "the CSS style properties one of them for",
"start": 3026.06,
"duration": 5.01
},
{
"text": "example is something like color so I can",
"start": 3028.19,
"duration": 5.34
},
{
"text": "update the color property and set it",
"start": 3031.07,
"duration": 6.87
},
{
"text": "equal to red so here now I'm saying when",
"start": 3033.53,
"duration": 6.9
},
{
"text": "you click on the red button go ahead and",
"start": 3037.94,
"duration": 4.65
},
{
"text": "run this function and what the function",
"start": 3040.43,
"duration": 4.59
},
{
"text": "should do is find the hello element",
"start": 3042.59,
"duration": 5.1
},
{
"text": "update it style what part of the style",
"start": 3045.02,
"duration": 3.84
},
{
"text": "update its color",
"start": 3047.69,
"duration": 3.54
},
{
"text": "what should we update it to we should",
"start": 3048.86,
"duration": 5.16
},
{
"text": "update it to red and I'm gonna do the",
"start": 3051.23,
"duration": 4.29
},
{
"text": "same thing for the other two buttons as",
"start": 3054.02,
"duration": 3.06
},
{
"text": "well and it's pretty similar codes I'm",
"start": 3055.52,
"duration": 4.26
},
{
"text": "just going to copy paste copy paste here",
"start": 3057.08,
"duration": 3.99
},
{
"text": "I'm gonna have one for changing the",
"start": 3059.78,
"duration": 3.27
},
{
"text": "color to blue when I click the blue",
"start": 3061.07,
"duration": 3.51
},
{
"text": "button you should change the color to",
"start": 3063.05,
"duration": 4.05
},
{
"text": "blue and then we'll do it one more time",
"start": 3064.58,
"duration": 5.34
},
{
"text": "change the font color to green when you",
"start": 3067.1,
"duration": 4.26
},
{
"text": "click on the green button you should",
"start": 3069.92,
"duration": 5.67
},
{
"text": "change the color to green so now when i",
"start": 3071.36,
"duration": 6.75
},
{
"text": "refresh the colors wml right now hello",
"start": 3075.59,
"duration": 4.11
},
{
"text": "by default it's just in black standard",
"start": 3078.11,
"duration": 4.68
},
{
"text": "font color for HTML I click red hello",
"start": 3079.7,
"duration": 4.74
},
{
"text": "changes to red I click blue it changes",
"start": 3082.79,
"duration": 3.96
},
{
"text": "to blue I click green it changes to",
"start": 3084.44,
"duration": 3.78
},
{
"text": "green so depending on what button I",
"start": 3086.75,
"duration": 3.72
},
{
"text": "click that triggers some event listener",
"start": 3088.22,
"duration": 4.5
},
{
"text": "that's going to then say when the button",
"start": 3090.47,
"duration": 4.05
},
{
"text": "is clicked run this function and what",
"start": 3092.72,
"duration": 4.2
},
{
"text": "the function does is it grabs this h1",
"start": 3094.52,
"duration": 4.37
},
{
"text": "element the element whose ID is hello",
"start": 3096.92,
"duration": 4.679
},
{
"text": "modifies it style updates its color",
"start": 3098.89,
"duration": 4.84
},
{
"text": "property to be something like red or",
"start": 3101.599,
"duration": 4.801
},
{
"text": "blue or green and that's showing that we",
"start": 3103.73,
"duration": 3.57
},
{
"text": "can modify style",
"start": 3106.4,
"duration": 2.82
},
{
"text": "in addition and just modifying the",
"start": 3107.3,
"duration": 5.519
},
{
"text": "content of the page itself but it turns",
"start": 3109.22,
"duration": 5.07
},
{
"text": "out that as you looked at me writing",
"start": 3112.819,
"duration": 2.79
},
{
"text": "that code something should have struck",
"start": 3114.29,
"duration": 3.69
},
{
"text": "you is probably not optimal design then",
"start": 3115.609,
"duration": 4.021
},
{
"text": "in general any time you find yourself",
"start": 3117.98,
"duration": 3.3
},
{
"text": "writing the same code again and again",
"start": 3119.63,
"duration": 3.209
},
{
"text": "and again especially if your copy",
"start": 3121.28,
"duration": 3.45
},
{
"text": "pasting that that is a generally a bad",
"start": 3122.839,
"duration": 3.931
},
{
"text": "sign usually a sign that there is some",
"start": 3124.73,
"duration": 5.4
},
{
"text": "better way of trying to modify of trying",
"start": 3126.77,
"duration": 4.98
},
{
"text": "to implement the behavior that I'm",
"start": 3130.13,
"duration": 3.33
},
{
"text": "trying to create and it turns out that",
"start": 3131.75,
"duration": 2.91
},
{
"text": "there is and there are a number of ways",
"start": 3133.46,
"duration": 4.109
},
{
"text": "that you could do this one way here is",
"start": 3134.66,
"duration": 4.439
},
{
"text": "that I might like to consolidate these",
"start": 3137.569,
"duration": 4.141
},
{
"text": "three event listeners into just like a",
"start": 3139.099,
"duration": 4.831
},
{
"text": "single function that is going to handle",
"start": 3141.71,
"duration": 4.77
},
{
"text": "changing the color to whatever the",
"start": 3143.93,
"duration": 4.35
},
{
"text": "button says the color should be changed",
"start": 3146.48,
"duration": 4.74
},
{
"text": "to but one problem here is that if I",
"start": 3148.28,
"duration": 4.74
},
{
"text": "just attach the same event listener to",
"start": 3151.22,
"duration": 4.32
},
{
"text": "all three of the buttons it's not going",
"start": 3153.02,
"duration": 4.98
},
{
"text": "to be clear to me when I click on the",
"start": 3155.54,
"duration": 3.87
},
{
"text": "button how does the button know what",
"start": 3158.0,
"duration": 4.02
},
{
"text": "color we should change the text to and",
"start": 3159.41,
"duration": 5.429
},
{
"text": "so to that effect we can add some",
"start": 3162.02,
"duration": 5.099
},
{
"text": "additional special attributes to a",
"start": 3164.839,
"duration": 4.5
},
{
"text": "particular HTML element that are called",
"start": 3167.119,
"duration": 5.131
},
{
"text": "data attributes where a data attribute",
"start": 3169.339,
"duration": 5.911
},
{
"text": "is my way of saying that I would like to",
"start": 3172.25,
"duration": 5.339
},
{
"text": "associate some data with this particular",
"start": 3175.25,
"duration": 4.98
},
{
"text": "h2 what HTML element we're here I can",
"start": 3177.589,
"duration": 7.651
},
{
"text": "say data - color equals red data - color",
"start": 3180.23,
"duration": 8.67
},
{
"text": "equals blue data - color equals green",
"start": 3185.24,
"duration": 5.849
},
{
"text": "data attributes always start with data",
"start": 3188.9,
"duration": 4.02
},
{
"text": "followed by a dash and then I can",
"start": 3191.089,
"duration": 3.75
},
{
"text": "specify really any name that I want for",
"start": 3192.92,
"duration": 3.39
},
{
"text": "some information that I would like to",
"start": 3194.839,
"duration": 4.26
},
{
"text": "store about the HTML element and here",
"start": 3196.31,
"duration": 4.89
},
{
"text": "the information I want to store is I",
"start": 3199.099,
"duration": 4.441
},
{
"text": "want to store data about what color you",
"start": 3201.2,
"duration": 4.23
},
{
"text": "should change the text to when the",
"start": 3203.54,
"duration": 3.45
},
{
"text": "button is clicked on and so what we're",
"start": 3205.43,
"duration": 3.51
},
{
"text": "gonna have the ability to do now is the",
"start": 3206.99,
"duration": 3.9
},
{
"text": "ability to say that if I have access to",
"start": 3208.94,
"duration": 4.77
},
{
"text": "this element this button I can access",
"start": 3210.89,
"duration": 6.09
},
{
"text": "its data color property to know whether",
"start": 3213.71,
"duration": 5.28
},
{
"text": "we should change the text to red or blue",
"start": 3216.98,
"duration": 4.32
},
{
"text": "or green by adding these data attributes",
"start": 3218.99,
"duration": 4.39
},
{
"text": "to these HTML elements",
"start": 3221.3,
"duration": 4.33
},
{
"text": "and so now what I want is some way of",
"start": 3223.38,
"duration": 4.439
},
{
"text": "getting all of these buttons now",
"start": 3225.63,
"duration": 5.31
},
{
"text": "document query selector as you recall",
"start": 3227.819,
"duration": 6.181
},
{
"text": "just gets one element it's just going to",
"start": 3230.94,
"duration": 4.919
},
{
"text": "get for me a single element and it's",
"start": 3234.0,
"duration": 3.93
},
{
"text": "gonna get the first one that it finds if",
"start": 3235.859,
"duration": 4.2
},
{
"text": "I want to get multiple elements what I",
"start": 3237.93,
"duration": 3.899
},
{
"text": "can do instead is something like",
"start": 3240.059,
"duration": 6.24
},
{
"text": "document dot query selector all query",
"start": 3241.829,
"duration": 5.97
},
{
"text": "selector all is going to return the same",
"start": 3246.299,
"duration": 3.421
},
{
"text": "thing the query selector does but",
"start": 3247.799,
"duration": 3.391
},
{
"text": "instead of query selector returning a",
"start": 3249.72,
"duration": 3.089
},
{
"text": "single element that matches what it",
"start": 3251.19,
"duration": 4.079
},
{
"text": "looks for query selector all is going to",
"start": 3252.809,
"duration": 5.04
},
{
"text": "return to me an array of all of the",
"start": 3255.269,
"duration": 4.651
},
{
"text": "elements that match my particular query",
"start": 3257.849,
"duration": 4.051
},
{
"text": "so if I want to select not just the",
"start": 3259.92,
"duration": 3.899
},
{
"text": "first button I find but all of the",
"start": 3261.9,
"duration": 4.109
},
{
"text": "buttons I find I can here say query",
"start": 3263.819,
"duration": 4.591
},
{
"text": "selector all for button and that will",
"start": 3266.009,
"duration": 3.961
},
{
"text": "give me back a JavaScript array the",
"start": 3268.41,
"duration": 4.08
},
{
"text": "equivalent of a list that represents all",
"start": 3269.97,
"duration": 5.16
},
{
"text": "of those buttons and we can actually",
"start": 3272.49,
"duration": 4.619
},
{
"text": "test what this looks like by looking at",
"start": 3275.13,
"duration": 4.709
},
{
"text": "things inside of the JavaScript console",
"start": 3277.109,
"duration": 6.091
},
{
"text": "that if I go ahead and refresh this page",
"start": 3279.839,
"duration": 6.72
},
{
"text": "colors I can open up the inspector go",
"start": 3283.2,
"duration": 5.25
},
{
"text": "into the JavaScript console and just as",
"start": 3286.559,
"duration": 3.81
},
{
"text": "you could see error messages here you",
"start": 3288.45,
"duration": 4.619
},
{
"text": "can also actually write JavaScript code",
"start": 3290.369,
"duration": 5.611
},
{
"text": "here as well so I can say something like",
"start": 3293.069,
"duration": 8.04
},
{
"text": "document query selector button say all",
"start": 3295.98,
"duration": 7.26
},
{
"text": "right what's going to happen when I try",
"start": 3301.109,
"duration": 3.93
},
{
"text": "and select for a button on this",
"start": 3303.24,
"duration": 5.01
},
{
"text": "particular page and what I get is all",
"start": 3305.039,
"duration": 5.01
},
{
"text": "right I get just this very first button",
"start": 3308.25,
"duration": 4.529
},
{
"text": "button whose data - color is equal to",
"start": 3310.049,
"duration": 4.23
},
{
"text": "red that's what I would expect query",
"start": 3312.779,
"duration": 3.3
},
{
"text": "selector just finds me one element and",
"start": 3314.279,
"duration": 2.941
},
{
"text": "it's going to find me",
"start": 3316.079,
"duration": 4.2
},
{
"text": "the very first element and likewise I",
"start": 3317.22,
"duration": 3.69
},
{
"text": "can say all right",
"start": 3320.279,
"duration": 2.911
},
{
"text": "instead of query selector let's do query",
"start": 3320.91,
"duration": 5.159
},
{
"text": "selector all and what I get back is a",
"start": 3323.19,
"duration": 4.26
},
{
"text": "node list which you can think of as kind",
"start": 3326.069,
"duration": 3.181
},
{
"text": "of like an array or a list in Python",
"start": 3327.45,
"duration": 4.29
},
{
"text": "that's got three buttons in it button 0",
"start": 3329.25,
"duration": 5.759
},
{
"text": "1 and 2 and just as with a list in",
"start": 3331.74,
"duration": 4.799
},
{
"text": "Python as you can index into things",
"start": 3335.009,
"duration": 3.961
},
{
"text": "arrays and python arrays in JavaScript",
"start": 3336.539,
"duration": 4.23
},
{
"text": "can be indexed into as well but if I",
"start": 3338.97,
"duration": 3.66
},
{
"text": "have something like constant Eames",
"start": 3340.769,
"duration": 7.05
},
{
"text": "equals Harry Ron and Hermione like a",
"start": 3342.63,
"duration": 8.34
},
{
"text": "array of 3 names I can say name square",
"start": 3347.819,
"duration": 5.49
},
{
"text": "bracket 0 to get the first name name",
"start": 3350.97,
"duration": 3.869
},
{
"text": "square bracket 1 to get the second one",
"start": 3353.309,
"duration": 3.51
},
{
"text": "name square bracket 2 to get the third",
"start": 3354.839,
"duration": 2.401
},
{
"text": "one for",
"start": 3356.819,
"duration": 2.221
},
{
"text": "example and that gives me each of the",
"start": 3357.24,
"duration": 3.96
},
{
"text": "individual elements in the array if I",
"start": 3359.04,
"duration": 3.24
},
{
"text": "want to get the whole length of the",
"start": 3361.2,
"duration": 4.32
},
{
"text": "array I can do names dot lengths to get",
"start": 3362.28,
"duration": 5.43
},
{
"text": "all right the length of the names array",
"start": 3365.52,
"duration": 4.05
},
{
"text": "happens to be three so just some",
"start": 3367.71,
"duration": 3.15
},
{
"text": "additional features that we have access",
"start": 3369.57,
"duration": 3.27
},
{
"text": "to if you happen to have an array of",
"start": 3370.86,
"duration": 2.82
},
{
"text": "things",
"start": 3372.84,
"duration": 2.73
},
{
"text": "turns out query selector all returns to",
"start": 3373.68,
"duration": 3.42
},
{
"text": "me a node list which is kind of like an",
"start": 3375.57,
"duration": 3.63
},
{
"text": "array and that's going to be useful",
"start": 3377.1,
"duration": 4.65
},
{
"text": "because when I say document query",
"start": 3379.2,
"duration": 5.07
},
{
"text": "selector all button I am saying get me",
"start": 3381.75,
"duration": 5.73
},
{
"text": "all of the buttons on the page and now",
"start": 3384.27,
"duration": 5.13
},
{
"text": "what I would like to do is effectively",
"start": 3387.48,
"duration": 5.25
},
{
"text": "loop over all of those buttons and say",
"start": 3389.4,
"duration": 5.94
},
{
"text": "for each of the buttons inside of this",
"start": 3392.73,
"duration": 4.65
},
{
"text": "list that comes back to me I would like",
"start": 3395.34,
"duration": 4.56
},
{
"text": "to add an event handler for when that",
"start": 3397.38,
"duration": 4.2
},
{
"text": "button is clicked on to say for each of",
"start": 3399.9,
"duration": 3.6
},
{
"text": "the buttons that comes back go ahead and",
"start": 3401.58,
"duration": 3.63
},
{
"text": "say when you're clicked on change the",
"start": 3403.5,
"duration": 4.8
},
{
"text": "color of the h1 element and so there are",
"start": 3405.21,
"duration": 4.8
},
{
"text": "a number of ways again that you could do",
"start": 3408.3,
"duration": 5.55
},
{
"text": "this but one way is to use a particular",
"start": 3410.01,
"duration": 7.41
},
{
"text": "property called for each and for each is",
"start": 3413.85,
"duration": 6.09
},
{
"text": "a function that accepts as an argument",
"start": 3417.42,
"duration": 5.189
},
{
"text": "another function where the idea is going",
"start": 3419.94,
"duration": 5.04
},
{
"text": "to be I would like to run a function for",
"start": 3422.609,
"duration": 5.101
},
{
"text": "each of the elements inside of an array",
"start": 3424.98,
"duration": 5.82
},
{
"text": "or inside of a node list for example so",
"start": 3427.71,
"duration": 6.84
},
{
"text": "here I can say for each button go ahead",
"start": 3430.8,
"duration": 5.79
},
{
"text": "and run this function this is going to",
"start": 3434.55,
"duration": 3.72
},
{
"text": "be a function now that takes something",
"start": 3436.59,
"duration": 3.87
},
{
"text": "as input it's going to take one of the",
"start": 3438.27,
"duration": 4.26
},
{
"text": "elements in the list as input something",
"start": 3440.46,
"duration": 5.46
},
{
"text": "like a button and now for each button",
"start": 3442.53,
"duration": 5.96
},
{
"text": "what would I like to do for that button",
"start": 3445.92,
"duration": 5.43
},
{
"text": "well when the button is clicked on",
"start": 3448.49,
"duration": 6.1
},
{
"text": "button dot on click then go ahead and",
"start": 3451.35,
"duration": 9.269
},
{
"text": "run a function that is going to document",
"start": 3454.59,
"duration": 9.72
},
{
"text": "query selector get me the element whose",
"start": 3460.619,
"duration": 8.431
},
{
"text": "ID is hello change its style within the",
"start": 3464.31,
"duration": 7.14
},
{
"text": "style change its color and what do I",
"start": 3469.05,
"duration": 4.319
},
{
"text": "want to change its color to well I have",
"start": 3471.45,
"duration": 3.78
},
{
"text": "access to this button this argument to",
"start": 3473.369,
"duration": 3.961
},
{
"text": "the function is whichever button I'm",
"start": 3475.23,
"duration": 3.36
},
{
"text": "currently trying to add an event",
"start": 3477.33,
"duration": 3.84
},
{
"text": "listener for and in order to access its",
"start": 3478.59,
"duration": 4.89
},
{
"text": "data properties I can access a special",
"start": 3481.17,
"duration": 4.8
},
{
"text": "property of an HTML element called it's",
"start": 3483.48,
"duration": 5.04
},
{
"text": "a data set property and then I can say",
"start": 3485.97,
"duration": 4.8
},
{
"text": "something like button data set",
"start": 3488.52,
"duration": 4.95
},
{
"text": "color to get at the data - color",
"start": 3490.77,
"duration": 5.85
},
{
"text": "attribute so a lot of stuff going on",
"start": 3493.47,
"duration": 4.29
},
{
"text": "here let's go ahead and try and read",
"start": 3496.62,
"duration": 2.79
},
{
"text": "through this entire thing and just get a",
"start": 3497.76,
"duration": 2.88
},
{
"text": "feel for what's happening because we",
"start": 3499.41,
"duration": 2.91
},
{
"text": "have functions nested within other",
"start": 3500.64,
"duration": 3.42
},
{
"text": "functions nested within other functions",
"start": 3502.32,
"duration": 4.56
},
{
"text": "up at the very top I said add an event",
"start": 3504.06,
"duration": 4.77
},
{
"text": "listener to the document when the",
"start": 3506.88,
"duration": 3.99
},
{
"text": "documents Dom content is loaded meaning",
"start": 3508.83,
"duration": 3.6
},
{
"text": "all of the content of the page is done",
"start": 3510.87,
"duration": 3.96
},
{
"text": "loading go ahead and run this function",
"start": 3512.43,
"duration": 5.4
},
{
"text": "this is the body of the function so what",
"start": 3514.83,
"duration": 4.32
},
{
"text": "do I want to do when the page is done",
"start": 3517.83,
"duration": 3.48
},
{
"text": "loading I'm going to document dot query",
"start": 3519.15,
"duration": 4.65
},
{
"text": "selector all looking for all of the",
"start": 3521.31,
"duration": 4.74
},
{
"text": "buttons and if I wanted to if there",
"start": 3523.8,
"duration": 3.81
},
{
"text": "could be more buttons I could have added",
"start": 3526.05,
"duration": 3.24
},
{
"text": "a class to these buttons and just look",
"start": 3527.61,
"duration": 3.36
},
{
"text": "for things of the particular class query",
"start": 3529.29,
"duration": 3.3
},
{
"text": "selector all just returns all of the",
"start": 3530.97,
"duration": 3.48
},
{
"text": "elements that match a particular query",
"start": 3532.59,
"duration": 5.4
},
{
"text": "and then I'm saying for each of those",
"start": 3534.45,
"duration": 5.13
},
{
"text": "buttons for each of the buttons that",
"start": 3537.99,
"duration": 3.93
},
{
"text": "came back I would like to run a function",
"start": 3539.58,
"duration": 4.5
},
{
"text": "on each of those buttons I'm basically",
"start": 3541.92,
"duration": 3.66
},
{
"text": "saying if I have three buttons that came",
"start": 3544.08,
"duration": 3.36
},
{
"text": "back let me run a function on the first",
"start": 3545.58,
"duration": 3.48
},
{
"text": "button then the same function on the",
"start": 3547.44,
"duration": 3.39
},
{
"text": "second button then the same function on",
"start": 3549.06,
"duration": 3.57
},
{
"text": "the third button and what is that",
"start": 3550.83,
"duration": 4.2
},
{
"text": "function well it's this function here a",
"start": 3552.63,
"duration": 5.16
},
{
"text": "function that takes as input the button",
"start": 3555.03,
"duration": 4.41
},
{
"text": "its first gonna pass in as input the",
"start": 3557.79,
"duration": 3.45
},
{
"text": "first button then the second button then",
"start": 3559.44,
"duration": 4.47
},
{
"text": "the third and what this function does is",
"start": 3561.24,
"duration": 5.55
},
{
"text": "it adds an onclick handler to the button",
"start": 3563.91,
"duration": 5.28
},
{
"text": "it says when the button is clicked on go",
"start": 3566.79,
"duration": 4.26
},
{
"text": "ahead and run this other function and",
"start": 3569.19,
"duration": 3.9
},
{
"text": "this function now is the function that",
"start": 3571.05,
"duration": 3.93
},
{
"text": "will run when the button is clicked on",
"start": 3573.09,
"duration": 4.38
},
{
"text": "to say when the button is clicked on get",
"start": 3574.98,
"duration": 5.84
},
{
"text": "me the hello element change its color to",
"start": 3577.47,
"duration": 6.99
},
{
"text": "button dataset color and button dataset",
"start": 3580.82,
"duration": 5.95
},
{
"text": "that color takes a button takes an HTML",
"start": 3584.46,
"duration": 4.68
},
{
"text": "element like this one here and accesses",
"start": 3586.77,
"duration": 4.47
},
{
"text": "its data set all of its data properties",
"start": 3589.14,
"duration": 5.37
},
{
"text": "and specifically accesses the color data",
"start": 3591.24,
"duration": 5.1
},
{
"text": "property which in this case is equal to",
"start": 3594.51,
"duration": 3.45
},
{
"text": "red and that is what we would like to",
"start": 3596.34,
"duration": 4.98
},
{
"text": "set color equal to so a little bit more",
"start": 3597.96,
"duration": 4.41
},
{
"text": "complexity we've seen before",
"start": 3601.32,
"duration": 3.81
},
{
"text": "but now we've been able to reduce what",
"start": 3602.37,
"duration": 5.16
},
{
"text": "was three different event handlers into",
"start": 3605.13,
"duration": 4.74
},
{
"text": "just a single one and now this is going",
"start": 3607.53,
"duration": 4.14
},
{
"text": "to work the same way change it to red",
"start": 3609.87,
"duration": 4.8
},
{
"text": "blue and green all by just using those",
"start": 3611.67,
"duration": 4.83
},
{
"text": "data properties that we have access to",
"start": 3614.67,
"duration": 3.96
},
{
"text": "and so when in doubt about how these",
"start": 3616.5,
"duration": 3.48
},
{
"text": "things are working about what query",
"start": 3618.63,
"duration": 3.09
},
{
"text": "selector is returning the JavaScript",
"start": 3619.98,
"duration": 3.21
},
{
"text": "console can be a very powerful tool for",
"start": 3621.72,
"duration": 2.79
},
{
"text": "this so you can go into the JavaScript",
"start": 3623.19,
"duration": 1.89
},
{
"text": "console",
"start": 3624.51,
"duration": 2.49
},
{
"text": "and actually manipulate things you can",
"start": 3625.08,
"duration": 4.02
},
{
"text": "running run queries you can run",
"start": 3627.0,
"duration": 3.78
},
{
"text": "functions you can even modify their",
"start": 3629.1,
"duration": 3.66
},
{
"text": "values of variables like if I go back",
"start": 3630.78,
"duration": 5.49
},
{
"text": "for instance to counter dot HTML or head",
"start": 3632.76,
"duration": 6.27
},
{
"text": "this counter that's counting 0 1 2 3 4",
"start": 3636.27,
"duration": 5.22
},
{
"text": "if I wanted to I could say something",
"start": 3639.03,
"duration": 6.0
},
{
"text": "like counter equals 27 just like change",
"start": 3641.49,
"duration": 5.85
},
{
"text": "the value of the counter nothing appears",
"start": 3645.03,
"duration": 3.96
},
{
"text": "to have changed on the page I didn't say",
"start": 3647.34,
"duration": 3.96
},
{
"text": "update anything on the page but now next",
"start": 3648.99,
"duration": 4.02
},
{
"text": "time I run count it's going to update",
"start": 3651.3,
"duration": 3.9
},
{
"text": "the value of the count to 28 because I",
"start": 3653.01,
"duration": 3.84
},
{
"text": "had updated the value inside of the",
"start": 3655.2,
"duration": 3.3
},
{
"text": "JavaScript console it's going to",
"start": 3656.85,
"duration": 3.66
},
{
"text": "increment that value display that value",
"start": 3658.5,
"duration": 4.53
},
{
"text": "inside of the h1 element so you can",
"start": 3660.51,
"duration": 4.26
},
{
"text": "modify variables that you can run",
"start": 3663.03,
"duration": 4.56
},
{
"text": "functions you can run document query",
"start": 3664.77,
"duration": 4.23
},
{
"text": "selector to figure out what particular",
"start": 3667.59,
"duration": 3.3
},
{
"text": "elements are going to come back all",
"start": 3669.0,
"duration": 3.27
},
{
"text": "through the use of the javascript",
"start": 3670.89,
"duration": 3.33
},
{
"text": "console which can be a very very",
"start": 3672.27,
"duration": 3.81
},
{
"text": "powerful tool especially as you begin",
"start": 3674.22,
"duration": 3.99
},
{
"text": "working on trying to debug these",
"start": 3676.08,
"duration": 4.32
},
{
"text": "programs and trying to figure out what",
"start": 3678.21,
"duration": 4.26
},
{
"text": "might be wrong with them it turns out",
"start": 3680.4,
"duration": 3.51
},
{
"text": "too that there are other changes that we",
"start": 3682.47,
"duration": 3.09
},
{
"text": "can make in order to optimize our code a",
"start": 3683.91,
"duration": 3.03
},
{
"text": "little bit more in order to make it a",
"start": 3685.56,
"duration": 3.33
},
{
"text": "little bit more succinct and one way is",
"start": 3686.94,
"duration": 3.18
},
{
"text": "that in more recent versions of",
"start": 3688.89,
"duration": 2.49
},
{
"text": "JavaScript they've introduced a",
"start": 3690.12,
"duration": 3.3
},
{
"text": "particular notation for functions called",
"start": 3691.38,
"duration": 3.87
},
{
"text": "the arrow notation for functions and",
"start": 3693.42,
"duration": 3.18
},
{
"text": "I'll just show it to you because it'll",
"start": 3695.25,
"duration": 3.45
},
{
"text": "come up but often times instead of using",
"start": 3696.6,
"duration": 3.93
},
{
"text": "the keyword function before introducing",
"start": 3698.7,
"duration": 3.72
},
{
"text": "a function you'll just have something",
"start": 3700.53,
"duration": 6.63
},
{
"text": "like button and then arrow the curly",
"start": 3702.42,
"duration": 6.12
},
{
"text": "braces and strictly speaking you don't",
"start": 3707.16,
"duration": 2.67
},
{
"text": "even need the parentheses around the",
"start": 3708.54,
"duration": 3.99
},
{
"text": "input where button arrow and then in",
"start": 3709.83,
"duration": 4.74
},
{
"text": "these curly braces some code just means",
"start": 3712.53,
"duration": 3.48
},
{
"text": "here is going to be a function that",
"start": 3714.57,
"duration": 3.63
},
{
"text": "takes as input a variable called button",
"start": 3716.01,
"duration": 5.16
},
{
"text": "and then runs this particular block of",
"start": 3718.2,
"duration": 5.16
},
{
"text": "code when that function is run and",
"start": 3721.17,
"duration": 4.23
},
{
"text": "likewise if a function takes no input",
"start": 3723.36,
"duration": 3.75
},
{
"text": "like this function up here you could",
"start": 3725.4,
"duration": 3.6
},
{
"text": "express it using arrow notation with",
"start": 3727.11,
"duration": 5.37
},
{
"text": "just parentheses a arrow block and so",
"start": 3729.0,
"duration": 5.16
},
{
"text": "this is often a notation that you'll see",
"start": 3732.48,
"duration": 3.57
},
{
"text": "in Java scripts if you ever see it know",
"start": 3734.16,
"duration": 3.33
},
{
"text": "that that's really just shorthand for",
"start": 3736.05,
"duration": 3.09
},
{
"text": "creating a function whatever is to the",
"start": 3737.49,
"duration": 3.75
},
{
"text": "left of the arrow sign is the input to",
"start": 3739.14,
"duration": 3.66
},
{
"text": "the function and whatever is to the",
"start": 3741.24,
"duration": 3.3
},
{
"text": "right of the arrow is what code should",
"start": 3742.8,
"duration": 3.9
},
{
"text": "actually run when the function body gets",
"start": 3744.54,
"duration": 4.05
},
{
"text": "executed when the function is called",
"start": 3746.7,
"duration": 4.53
},
{
"text": "upon so what other changes might we want",
"start": 3748.59,
"duration": 5.13
},
{
"text": "to make two colors dot HTML well if we",
"start": 3751.23,
"duration": 4.41
},
{
"text": "look back at colors dot HTML here's what",
"start": 3753.72,
"duration": 3.21
},
{
"text": "it looks like now we've got a heading",
"start": 3755.64,
"duration": 2.78
},
{
"text": "that says hello and then",
"start": 3756.93,
"duration": 3.439
},
{
"text": "to change the color to red or blue or",
"start": 3758.42,
"duration": 4.439
},
{
"text": "green for example we might instead if we",
"start": 3760.369,
"duration": 4.381
},
{
"text": "want the user to choose from one from a",
"start": 3762.859,
"duration": 3.901
},
{
"text": "number of options decide upon the user",
"start": 3764.75,
"duration": 4.349
},
{
"text": "interface choice of using a drop-down",
"start": 3766.76,
"duration": 3.809
},
{
"text": "instead of a bunch of buttons for",
"start": 3769.099,
"duration": 3.45
},
{
"text": "example and JavaScript supports that as",
"start": 3770.569,
"duration": 3.061
},
{
"text": "well and we'll use this as an",
"start": 3772.549,
"duration": 2.911
},
{
"text": "opportunity to explore some of the other",
"start": 3773.63,
"duration": 3.719
},
{
"text": "event handlers that exist within",
"start": 3775.46,
"duration": 5.19
},
{
"text": "JavaScript so for example instead of",
"start": 3777.349,
"duration": 5.52
},
{
"text": "having these all inside of buttons I can",
"start": 3780.65,
"duration": 3.87
},
{
"text": "make my life a little bit easier by",
"start": 3782.869,
"duration": 4.351
},
{
"text": "making this a select drop-down where the",
"start": 3784.52,
"duration": 4.829
},
{
"text": "Select is going to have an option whose",
"start": 3787.22,
"duration": 4.139
},
{
"text": "value is I'll say black is the default",
"start": 3789.349,
"duration": 3.99
},
{
"text": "option and I'll say black and then we'll",
"start": 3791.359,
"duration": 3.871
},
{
"text": "add another option whose value is red",
"start": 3793.339,
"duration": 4.591
},
{
"text": "and then we say red and the value is",
"start": 3795.23,
"duration": 4.41
},
{
"text": "what we'll get in JavaScript when we try",
"start": 3797.93,
"duration": 3.149
},
{
"text": "and extract the value of a particular",
"start": 3799.64,
"duration": 3.719
},
{
"text": "select drop-down well it's in between",
"start": 3801.079,
"duration": 4.201
},
{
"text": "the option tags themselves is what the",
"start": 3803.359,
"duration": 3.631
},
{
"text": "user is going to see on the page when",
"start": 3805.28,
"duration": 2.7
},
{
"text": "they actually view it so I'm",
"start": 3806.99,
"duration": 3.569
},
{
"text": "capitalizing it just for them option",
"start": 3807.98,
"duration": 4.139
},
{
"text": "value equals blue",
"start": 3810.559,
"duration": 3.841
},
{
"text": "that'll be blue and then option value",
"start": 3812.119,
"duration": 5.43
},
{
"text": "equals green and that'll be green so now",
"start": 3814.4,
"duration": 5.429
},
{
"text": "what the user sees is they see hello and",
"start": 3817.549,
"duration": 3.78
},
{
"text": "then a drop-down menu where they can",
"start": 3819.829,
"duration": 3.54
},
{
"text": "choose from a list of colors rather than",
"start": 3821.329,
"duration": 4.5
},
{
"text": "click buttons in order to do so and now",
"start": 3823.369,
"duration": 4.44
},
{
"text": "of course this select drop-down doesn't",
"start": 3825.829,
"duration": 3.661
},
{
"text": "do anything at the moment but I can",
"start": 3827.809,
"duration": 4.591
},
{
"text": "modify it so that it does so now instead",
"start": 3829.49,
"duration": 4.92
},
{
"text": "of selecting for all of the buttons and",
"start": 3832.4,
"duration": 3.54
},
{
"text": "doing something with all the buttons we",
"start": 3834.41,
"duration": 3.419
},
{
"text": "don't have any buttons anymore what I do",
"start": 3835.94,
"duration": 6.75
},
{
"text": "have is I have a select drop-down and",
"start": 3837.829,
"duration": 7.411
},
{
"text": "now just as we've seen like on click to",
"start": 3842.69,
"duration": 3.96
},
{
"text": "say when you click on something as we've",
"start": 3845.24,
"duration": 3.089
},
{
"text": "seen Dom content loaded as an event",
"start": 3846.65,
"duration": 4.11
},
{
"text": "there's another event called on change",
"start": 3848.329,
"duration": 4.111
},
{
"text": "which applies to things like select",
"start": 3850.76,
"duration": 4.26
},
{
"text": "dropdowns where when something changes",
"start": 3852.44,
"duration": 3.899
},
{
"text": "in the select drop-down when a user",
"start": 3855.02,
"duration": 2.64
},
{
"text": "chooses something different",
"start": 3856.339,
"duration": 4.23
},
{
"text": "I can run some code for example so I can",
"start": 3857.66,
"duration": 5.1
},
{
"text": "run a function that in this case is",
"start": 3860.569,
"duration": 4.55
},
{
"text": "going to take document query selector",
"start": 3862.76,
"duration": 3.599
},
{
"text": "hello",
"start": 3865.119,
"duration": 3.48
},
{
"text": "meaning get me the hello HTML element",
"start": 3866.359,
"duration": 4.861
},
{
"text": "change its style what part of the style",
"start": 3868.599,
"duration": 4.96
},
{
"text": "changed its color and I want to change",
"start": 3871.22,
"duration": 3.66
},
{
"text": "it to something I want to change it to",
"start": 3873.559,
"duration": 5.04
},
{
"text": "the value of this select drop-down but",
"start": 3874.88,
"duration": 5.16
},
{
"text": "how do I get access to this particular",
"start": 3878.599,
"duration": 4.171
},
{
"text": "select drop-down well in JavaScript we",
"start": 3880.04,
"duration": 4.95
},
{
"text": "have access to a special value called",
"start": 3882.77,
"duration": 5.64
},
{
"text": "this and this has special meaning in",
"start": 3884.99,
"duration": 5.01
},
{
"text": "JavaScript and its meaning varies based",
"start": 3888.41,
"duration": 3.84
},
{
"text": "on context but in the context of an",
"start": 3890.0,
"duration": 3.96
},
{
"text": "event handler a function that is called",
"start": 3892.25,
"duration": 4.29
},
{
"text": "when a particular event happens this is",
"start": 3893.96,
"duration": 4.47
},
{
"text": "going to be a special keyword that",
"start": 3896.54,
"duration": 4.32
},
{
"text": "always refers to the thing that received",
"start": 3898.43,
"duration": 3.3
},
{
"text": "the event",
"start": 3900.86,
"duration": 2.85
},
{
"text": "so what received the event it was the",
"start": 3901.73,
"duration": 3.72
},
{
"text": "select drop-down that is what received",
"start": 3903.71,
"duration": 4.29
},
{
"text": "the event is being changed and so this",
"start": 3905.45,
"duration": 4.8
},
{
"text": "is going to be a special keyword that",
"start": 3908.0,
"duration": 4.17
},
{
"text": "always refers to that that always refers",
"start": 3910.25,
"duration": 4.05
},
{
"text": "to the drop-down menu where I made a",
"start": 3912.17,
"duration": 3.93
},
{
"text": "different selection so if I want to get",
"start": 3914.3,
"duration": 3.54
},
{
"text": "the value of that drop-down menu what it",
"start": 3916.1,
"duration": 4.14
},
{
"text": "is the user actually selected I can just",
"start": 3917.84,
"duration": 5.04
},
{
"text": "say this dot value to mean get that",
"start": 3920.24,
"duration": 4.74
},
{
"text": "drop-down menu and get at the value the",
"start": 3922.88,
"duration": 3.81
},
{
"text": "thing that the user is selected in that",
"start": 3924.98,
"duration": 4.08
},
{
"text": "idea and now much more succinctly than",
"start": 3926.69,
"duration": 4.92
},
{
"text": "before I've been able to implement the",
"start": 3929.06,
"duration": 4.56
},
{
"text": "same kind of idea says hello right now",
"start": 3931.61,
"duration": 3.66
},
{
"text": "in black but if I choose from the",
"start": 3933.62,
"duration": 3.48
},
{
"text": "drop-down menu to change its color to",
"start": 3935.27,
"duration": 3.72
},
{
"text": "something like red for example color",
"start": 3937.1,
"duration": 4.23
},
{
"text": "changes to red if I instead choose blue",
"start": 3938.99,
"duration": 4.59
},
{
"text": "it changes to blue green changes to",
"start": 3941.33,
"duration": 4.98
},
{
"text": "green I choose black it changes back to",
"start": 3943.58,
"duration": 5.04
},
{
"text": "black so now I have this ability to",
"start": 3946.31,
"duration": 4.11
},
{
"text": "detect these other types of events and",
"start": 3948.62,
"duration": 4.05
},
{
"text": "respond to them as well and there are",
"start": 3950.42,
"duration": 4.65
},
{
"text": "many many different events that exist in",
"start": 3952.67,
"duration": 4.2
},
{
"text": "JavaScript there's on-click which we've",
"start": 3955.07,
"duration": 4.2
},
{
"text": "seen already on mouse-over can detect",
"start": 3956.87,
"duration": 3.84
},
{
"text": "like when you mouse over something when",
"start": 3959.27,
"duration": 2.64
},
{
"text": "you're hovering over a particular",
"start": 3960.71,
"duration": 2.97
},
{
"text": "element if you've ever seen web sites",
"start": 3961.91,
"duration": 3.54
},
{
"text": "that somehow respond when your mouse",
"start": 3963.68,
"duration": 3.57
},
{
"text": "moves over something that can be how",
"start": 3965.45,
"duration": 4.29
},
{
"text": "it's implemented on key down and onkeyup",
"start": 3967.25,
"duration": 4.23
},
{
"text": "can respond to keyboard event something",
"start": 3969.74,
"duration": 4.32
},
{
"text": "like when you press a key on the",
"start": 3971.48,
"duration": 4.14
},
{
"text": "keyboard when you press down on the key",
"start": 3974.06,
"duration": 3.69
},
{
"text": "that's on key down and when you lift",
"start": 3975.62,
"duration": 3.9
},
{
"text": "your finger off the key that's on key up",
"start": 3977.75,
"duration": 4.14
},
{
"text": "and there are other events as well many",
"start": 3979.52,
"duration": 3.78
},
{
"text": "more events that are just listed here",
"start": 3981.89,
"duration": 3.93
},
{
"text": "that you can listen for and respond to",
"start": 3983.3,
"duration": 4.38
},
{
"text": "so that you can really interact with the",
"start": 3985.82,
"duration": 3.99
},
{
"text": "user based on what it is that they're",
"start": 3987.68,
"duration": 4.23
},
{
"text": "doing so now let's take a look at an",
"start": 3989.81,
"duration": 3.99
},
{
"text": "example of how we can use some of these",
"start": 3991.91,
"duration": 3.96
},
{
"text": "events to now begin to create a little",
"start": 3993.8,
"duration": 4.05
},
{
"text": "bit of a more interesting application",
"start": 3995.87,
"duration": 4.23
},
{
"text": "we'll go ahead and build a to-do list",
"start": 3997.85,
"duration": 4.1
},
{
"text": "application this time using exclusively",
"start": 4000.1,
"duration": 3.78
},
{
"text": "JavaScript we've seen to-do lists before",
"start": 4001.95,
"duration": 3.91
},
{
"text": "that involve communicating with a server",
"start": 4003.88,
"duration": 3.99
},
{
"text": "making requests and responses will now",
"start": 4005.86,
"duration": 4.08
},
{
"text": "build it to-do list that only uses",
"start": 4007.87,
"duration": 4.53
},
{
"text": "JavaScript to do so so I'll create a new",
"start": 4009.94,
"duration": 7.65
},
{
"text": "file called tasks HTML and we'll use a",
"start": 4012.4,
"duration": 7.5
},
{
"text": "we'll create a head section whose title",
"start": 4017.59,
"duration": 5.67
},
{
"text": "is tasks and a body section and inside",
"start": 4019.9,
"duration": 5.1
},
{
"text": "the body of the page I'll go ahead and",
"start": 4023.26,
"duration": 2.79
},
{
"text": "have a heading that says",
"start": 4025.0,
"duration": 4.08
},
{
"text": "tasks and underneath that I want an",
"start": 4026.05,
"duration": 5.46
},
{
"text": "unordered list of all of my tasks so",
"start": 4029.08,
"duration": 4.05
},
{
"text": "I'll have an unordered list I'll give it",
"start": 4031.51,
"duration": 3.9
},
{
"text": "an ID of tasks just for good measure so",
"start": 4033.13,
"duration": 4.05
},
{
"text": "I can reference it later but initially",
"start": 4035.41,
"duration": 4.32
},
{
"text": "nothing's going to be in here but what",
"start": 4037.18,
"duration": 4.08
},
{
"text": "I'll have underneath the unordered list",
"start": 4039.73,
"duration": 4.92
},
{
"text": "is a form a form where I can submit a",
"start": 4041.26,
"duration": 5.52
},
{
"text": "new task for example so I'll give myself",
"start": 4044.65,
"duration": 4.74
},
{
"text": "an input field also given an ID the ID",
"start": 4046.78,
"duration": 4.83
},
{
"text": "will be tasks singular for the new task",
"start": 4049.39,
"duration": 5.43
},
{
"text": "that I am typing in the placeholder will",
"start": 4051.61,
"duration": 5.1
},
{
"text": "be new tasks just so the user knows what",
"start": 4054.82,
"duration": 3.78
},
{
"text": "to type in and the type of the input",
"start": 4056.71,
"duration": 3.78
},
{
"text": "field will be text so I have an input",
"start": 4058.6,
"duration": 3.54
},
{
"text": "field where the user can type in some",
"start": 4060.49,
"duration": 3.84
},
{
"text": "new tasks and I'll also add an input",
"start": 4062.14,
"duration": 3.93
},
{
"text": "field for good measure whose type is",
"start": 4064.33,
"duration": 3.93
},
{
"text": "submit that allows the user to submit a",
"start": 4066.07,
"duration": 4.83
},
{
"text": "new task once they've created it so if I",
"start": 4068.26,
"duration": 6.09
},
{
"text": "open up tasks dot HTML here's then what",
"start": 4070.9,
"duration": 5.67
},
{
"text": "I see big heading there is technically",
"start": 4074.35,
"duration": 4.23
},
{
"text": "an unordered list underneath it here but",
"start": 4076.57,
"duration": 3.69
},
{
"text": "there's nothing in that unordered list",
"start": 4078.58,
"duration": 3.72
},
{
"text": "yet so it just shows up as empty then a",
"start": 4080.26,
"duration": 3.39
},
{
"text": "text field where I can type in a task",
"start": 4082.3,
"duration": 3.54
},
{
"text": "and then a submit button where I can",
"start": 4083.65,
"duration": 5.85
},
{
"text": "submit my new task so now I'd like some",
"start": 4085.84,
"duration": 5.25
},
{
"text": "JavaScript such that when I submit this",
"start": 4089.5,
"duration": 4.53
},
{
"text": "form we actually do something so add a",
"start": 4091.09,
"duration": 3.69
},
{
"text": "script tag",
"start": 4094.03,
"duration": 5.37
},
{
"text": "I want this JavaScript to run after the",
"start": 4094.78,
"duration": 8.94
},
{
"text": "Dom content is loaded so we'll go ahead",
"start": 4099.4,
"duration": 5.85
},
{
"text": "and add the usual Dom content loaded",
"start": 4103.72,
"duration": 4.65
},
{
"text": "event listener and now I want to run",
"start": 4105.25,
"duration": 5.91
},
{
"text": "code when the form is submitted so I can",
"start": 4108.37,
"duration": 7.949
},
{
"text": "say document query selector form dot on",
"start": 4111.16,
"duration": 7.77
},
{
"text": "submit equals and then I want to run a",
"start": 4116.319,
"duration": 4.29
},
{
"text": "function and I could use the keyword",
"start": 4118.93,
"duration": 2.88
},
{
"text": "function again but I can just use an",
"start": 4120.609,
"duration": 2.371
},
{
"text": "arrow function which would be a little",
"start": 4121.81,
"duration": 2.52
},
{
"text": "bit faster to type just say alright",
"start": 4122.98,
"duration": 3.39
},
{
"text": "here's the function that I want to run",
"start": 4124.33,
"duration": 4.56
},
{
"text": "when the form is submitted and what",
"start": 4126.37,
"duration": 4.44
},
{
"text": "would I like to do well I'd first like",
"start": 4128.89,
"duration": 3.33
},
{
"text": "to figure out alright what did the user",
"start": 4130.81,
"duration": 3.84
},
{
"text": "actually type in and what the user typed",
"start": 4132.22,
"duration": 4.59
},
{
"text": "in well that'll be document query",
"start": 4134.65,
"duration": 7.8
},
{
"text": "selector task dot value get me the",
"start": 4136.81,
"duration": 7.17
},
{
"text": "element with ID task that's the input",
"start": 4142.45,
"duration": 4.2
},
{
"text": "field dot value gets the value of the",
"start": 4143.98,
"duration": 3.99
},
{
"text": "input field which is what the user",
"start": 4146.65,
"duration": 4.439
},
{
"text": "actually typed in and I can save that as",
"start": 4147.97,
"duration": 6.96
},
{
"text": "like Const tasks that is what it is the",
"start": 4151.089,
"duration": 6.96
},
{
"text": "user typed in and if I'm curious as to",
"start": 4154.93,
"duration": 4.56
},
{
"text": "what the user typed in I can",
"start": 4158.049,
"duration": 3.991
},
{
"text": "actually print it out to the JavaScript",
"start": 4159.49,
"duration": 4.32
},
{
"text": "console and the way to do that is using",
"start": 4162.04,
"duration": 4.11
},
{
"text": "a special function called console.log",
"start": 4163.81,
"duration": 4.65
},
{
"text": "and that just logs something to the",
"start": 4166.15,
"duration": 3.63
},
{
"text": "console the equivalent of printing",
"start": 4168.46,
"duration": 2.7
},
{
"text": "something out in Python where just shows",
"start": 4169.78,
"duration": 3.24
},
{
"text": "up in the Python terminal here this is",
"start": 4171.16,
"duration": 3.42
},
{
"text": "going to show up in the JavaScript",
"start": 4173.02,
"duration": 4.11
},
{
"text": "console and one other thing I'll add is",
"start": 4174.58,
"duration": 4.89
},
{
"text": "by default forms will try and submit",
"start": 4177.13,
"duration": 3.57
},
{
"text": "when you press the submit button like",
"start": 4179.47,
"duration": 2.97
},
{
"text": "take you to another page we've seen this",
"start": 4180.7,
"duration": 3.45
},
{
"text": "before already in the context of Django",
"start": 4182.44,
"duration": 3.57
},
{
"text": "that when you submit a form it tries and",
"start": 4184.15,
"duration": 3.93
},
{
"text": "submits another web request if I want to",
"start": 4186.01,
"duration": 3.81
},
{
"text": "prevent that behavior stop the form from",
"start": 4188.08,
"duration": 3.69
},
{
"text": "submitting it's a stop form from",
"start": 4189.82,
"duration": 6.81
},
{
"text": "submitting I can return false at the end",
"start": 4191.77,
"duration": 6.78
},
{
"text": "of my form submission handler to say",
"start": 4196.63,
"duration": 3.66
},
{
"text": "don't actually submit the form we're",
"start": 4198.55,
"duration": 3.03
},
{
"text": "gonna do everything client-side",
"start": 4200.29,
"duration": 3.75
},
{
"text": "everything just inside of the browser so",
"start": 4201.58,
"duration": 3.93
},
{
"text": "now this won't quite work yet but it'll",
"start": 4204.04,
"duration": 3.6
},
{
"text": "be progress i refresh the page I'm gonna",
"start": 4205.51,
"duration": 3.63
},
{
"text": "open up the JavaScript console so I can",
"start": 4207.64,
"duration": 3.42
},
{
"text": "see what's going on if I add a task",
"start": 4209.14,
"duration": 4.52
},
{
"text": "something just like foo press submit",
"start": 4211.06,
"duration": 5.76
},
{
"text": "this now gets logged to the JavaScript",
"start": 4213.66,
"duration": 4.63
},
{
"text": "console it's the equivalent of a way of",
"start": 4216.82,
"duration": 3.18
},
{
"text": "like providing debugging information to",
"start": 4218.29,
"duration": 2.97
},
{
"text": "myself to know all right",
"start": 4220.0,
"duration": 3.96
},
{
"text": "I now have access to this value foo and",
"start": 4221.26,
"duration": 4.41
},
{
"text": "it's also telling me what line of code",
"start": 4223.96,
"duration": 4.77
},
{
"text": "logged it it was tasks HTML line 9 is",
"start": 4225.67,
"duration": 5.52
},
{
"text": "the line of code that logged foo and so",
"start": 4228.73,
"duration": 3.6
},
{
"text": "this can be useful when you're debugging",
"start": 4231.19,
"duration": 2.73
},
{
"text": "a program when you want to see what the",
"start": 4232.33,
"duration": 3.51
},
{
"text": "values of variables are you can just",
"start": 4233.92,
"duration": 4.23
},
{
"text": "print them out using console log to",
"start": 4235.84,
"duration": 3.45
},
{
"text": "figure out what's going on in your",
"start": 4238.15,
"duration": 3.71
},
{
"text": "program and any particular point in time",
"start": 4239.29,
"duration": 5.1
},
{
"text": "but what I want to do is not console dot",
"start": 4241.86,
"duration": 4.39
},
{
"text": "log n what I want to do is really create",
"start": 4244.39,
"duration": 4.86
},
{
"text": "a new element that I'm going to add into",
"start": 4246.25,
"duration": 6.06
},
{
"text": "my body of the HTML so how can I do that",
"start": 4249.25,
"duration": 5.07
},
{
"text": "well to create a new element for my",
"start": 4252.31,
"duration": 3.9
},
{
"text": "document I can run a function called",
"start": 4254.32,
"duration": 5.4
},
{
"text": "document dot create element followed by",
"start": 4256.21,
"duration": 5.34
},
{
"text": "what type of element do I want to create",
"start": 4259.72,
"duration": 4.68
},
{
"text": "well I have an unordered list a ul and",
"start": 4261.55,
"duration": 5.01
},
{
"text": "every item inside of an unordered list",
"start": 4264.4,
"duration": 5.25
},
{
"text": "is a list item in Li so I'll go ahead",
"start": 4266.56,
"duration": 6.59
},
{
"text": "and create an Li element a list item and",
"start": 4269.65,
"duration": 6.48
},
{
"text": "I'll save that in a variable that I'll",
"start": 4273.15,
"duration": 6.34
},
{
"text": "call Li so I've created a new list item",
"start": 4276.13,
"duration": 7.44
},
{
"text": "and this list items inner HTML the HTML",
"start": 4279.49,
"duration": 6.81
},
{
"text": "content inside of that list item well",
"start": 4283.57,
"duration": 5.04
},
{
"text": "that's just going to be tasks this",
"start": 4286.3,
"duration": 4.26
},
{
"text": "variable from up here which is whatever",
"start": 4288.61,
"duration": 4.65
},
{
"text": "the user typed in so I've now created",
"start": 4290.56,
"duration": 5.52
},
{
"text": "newest item and said what GML should go",
"start": 4293.26,
"duration": 4.35
},
{
"text": "inside of the list item it should be",
"start": 4296.08,
"duration": 4.35
},
{
"text": "whatever task the user typed in and now",
"start": 4297.61,
"duration": 5.91
},
{
"text": "I'm going to say document dot query",
"start": 4300.43,
"duration": 6.03
},
{
"text": "selector tasks get me the element whose",
"start": 4303.52,
"duration": 5.04
},
{
"text": "ideas tasks and that's gonna be this",
"start": 4306.46,
"duration": 4.05
},
{
"text": "unordered list here the unordered list",
"start": 4308.56,
"duration": 4.86
},
{
"text": "whose ideas tasks and if I have an HTML",
"start": 4310.51,
"duration": 5.58
},
{
"text": "element I can add a new element inside",
"start": 4313.42,
"duration": 7.86
},
{
"text": "of it by saying dot append Li and with",
"start": 4316.09,
"duration": 7.02
},
{
"text": "that now is going to do is it's going to",
"start": 4321.28,
"duration": 3.48
},
{
"text": "say get me the unordered list whose",
"start": 4323.11,
"duration": 3.39
},
{
"text": "ideas tasks get me the element whose",
"start": 4324.76,
"duration": 3.63
},
{
"text": "ideas tasks by a query selector here",
"start": 4326.5,
"duration": 4.71
},
{
"text": "once I have that element append to the",
"start": 4328.39,
"duration": 4.49
},
{
"text": "end of what's inside of that element",
"start": 4331.21,
"duration": 5.13
},
{
"text": "this value Li which happens to be this",
"start": 4332.88,
"duration": 5.56
},
{
"text": "new element that I've created a new list",
"start": 4336.34,
"duration": 4.5
},
{
"text": "item so I've been able to add a new HTML",
"start": 4338.44,
"duration": 4.35
},
{
"text": "element and this line of code is going",
"start": 4340.84,
"duration": 4.11
},
{
"text": "to say add it to the Dom add it to the",
"start": 4342.79,
"duration": 3.9
},
{
"text": "unordered list that I am here now",
"start": 4344.95,
"duration": 7.77
},
{
"text": "constructing so now I rerun this I see",
"start": 4346.69,
"duration": 7.71
},
{
"text": "tasks I type in something like foo I",
"start": 4352.72,
"duration": 4.17
},
{
"text": "press submit and alright foo now shows",
"start": 4354.4,
"duration": 3.99
},
{
"text": "up I type in something like a right to",
"start": 4356.89,
"duration": 3.93
},
{
"text": "leave that type in bar bar now shows up",
"start": 4358.39,
"duration": 5.19
},
{
"text": "I'd have been Baz Baz no shows up now",
"start": 4360.82,
"duration": 4.59
},
{
"text": "one minor user interface annoyance is",
"start": 4363.58,
"duration": 3.27
},
{
"text": "that it seems that every time I submit a",
"start": 4365.41,
"duration": 4.35
},
{
"text": "new task this input field retains the",
"start": 4366.85,
"duration": 4.89
},
{
"text": "value of what it used to be and that's",
"start": 4369.76,
"duration": 3.84
},
{
"text": "probably not what I want because I'd",
"start": 4371.74,
"duration": 3.21
},
{
"text": "rather it just clear out I've already",
"start": 4373.6,
"duration": 2.7
},
{
"text": "submitted the task no need for it to",
"start": 4374.95,
"duration": 3.27
},
{
"text": "stay there but that's easy to manipulate",
"start": 4376.3,
"duration": 4.17
},
{
"text": "in JavaScript if I want to clear out",
"start": 4378.22,
"duration": 4.2
},
{
"text": "this input field the input field whose",
"start": 4380.47,
"duration": 4.98
},
{
"text": "ID is task then all I need to do is say",
"start": 4382.42,
"duration": 6.93
},
{
"text": "document dot query selector task get me",
"start": 4385.45,
"duration": 6.96
},
{
"text": "that input field change its value equal",
"start": 4389.35,
"duration": 5.46
},
{
"text": "to the empty string equal to nothing",
"start": 4392.41,
"duration": 4.89
},
{
"text": "just to say clear out the value of what",
"start": 4394.81,
"duration": 4.02
},
{
"text": "happens to be inside of that input field",
"start": 4397.3,
"duration": 3.81
},
{
"text": "right now and now if i refresh the page",
"start": 4398.83,
"duration": 5.22
},
{
"text": "type in foo press submit input field",
"start": 4401.11,
"duration": 4.71
},
{
"text": "clears out and now I can type in",
"start": 4404.05,
"duration": 3.6
},
{
"text": "something like bar and then something",
"start": 4405.82,
"duration": 4.11
},
{
"text": "like Baz to continue to add tasks as",
"start": 4407.65,
"duration": 4.89
},
{
"text": "well now one thing that might be",
"start": 4409.93,
"duration": 3.6
},
{
"text": "slightly annoying is that I'm not",
"start": 4412.54,
"duration": 3.48
},
{
"text": "careful if I press submit well it",
"start": 4413.53,
"duration": 4.74
},
{
"text": "submits the empty string is a task and",
"start": 4416.02,
"duration": 4.14
},
{
"text": "so I just get this empty bullet point",
"start": 4418.27,
"duration": 4.02
},
{
"text": "that shows up here nice press submit and",
"start": 4420.16,
"duration": 3.81
},
{
"text": "I just get all of these empty bullet",
"start": 4422.29,
"duration": 3.24
},
{
"text": "points it might be nice from a user",
"start": 4423.97,
"duration": 2.939
},
{
"text": "experience perspective",
"start": 4425.53,
"duration": 3.45
},
{
"text": "if I were to not allow the user to do",
"start": 4426.909,
"duration": 4.141
},
{
"text": "that not allow them to submit a task if",
"start": 4428.98,
"duration": 3.719
},
{
"text": "they haven't actually typed something in",
"start": 4431.05,
"duration": 4.26
},
{
"text": "to the new task field and we can do that",
"start": 4432.699,
"duration": 4.951
},
{
"text": "just by modifying properties of elements",
"start": 4435.31,
"duration": 4.02
},
{
"text": "that it turns out that HTML elements",
"start": 4437.65,
"duration": 4.319
},
{
"text": "have a property called disabled that can",
"start": 4439.33,
"duration": 4.47
},
{
"text": "be true or false that allows us to",
"start": 4441.969,
"duration": 5.371
},
{
"text": "disable something like a button so if I",
"start": 4443.8,
"duration": 6.21
},
{
"text": "want to disable the submit button one",
"start": 4447.34,
"duration": 4.35
},
{
"text": "thing I might want to do first is give",
"start": 4450.01,
"duration": 3.99
},
{
"text": "this submit button an ID I'll give it an",
"start": 4451.69,
"duration": 4.77
},
{
"text": "ID of submit so that in my JavaScript",
"start": 4454.0,
"duration": 4.38
},
{
"text": "code I can reference the submit button",
"start": 4456.46,
"duration": 6.23
},
{
"text": "and now inside of this JavaScript code",
"start": 4458.38,
"duration": 7.83
},
{
"text": "when the Dom content is loaded by",
"start": 4462.69,
"duration": 7.38
},
{
"text": "default the submit button should be",
"start": 4466.21,
"duration": 6.239
},
{
"text": "disabled like when I first load the page",
"start": 4470.07,
"duration": 4.39
},
{
"text": "I don't want the submit button to be",
"start": 4472.449,
"duration": 3.361
},
{
"text": "enabled because I want the user to type",
"start": 4474.46,
"duration": 3.54
},
{
"text": "in a task first before I enable the",
"start": 4475.81,
"duration": 4.679
},
{
"text": "submit button so how do I do that well I",
"start": 4478.0,
"duration": 4.949
},
{
"text": "can document query selector get me the",
"start": 4480.489,
"duration": 4.261
},
{
"text": "element whose ID is submit get me that",
"start": 4482.949,
"duration": 3.571
},
{
"text": "submit button and just said it's",
"start": 4484.75,
"duration": 3.92
},
{
"text": "disabled property equal to true",
"start": 4486.52,
"duration": 4.29
},
{
"text": "javascript has boolean values true and",
"start": 4488.67,
"duration": 4.45
},
{
"text": "false I set the disabled value equal to",
"start": 4490.81,
"duration": 5.55
},
{
"text": "true to disable the submit button now if",
"start": 4493.12,
"duration": 5.19
},
{
"text": "i refresh the page I can type in a new",
"start": 4496.36,
"duration": 3.87
},
{
"text": "task but the submit button is disabled",
"start": 4498.31,
"duration": 3.659
},
{
"text": "it doesn't do anything now obviously I",
"start": 4500.23,
"duration": 2.969
},
{
"text": "don't want to keep it that way I'd like",
"start": 4501.969,
"duration": 2.701
},
{
"text": "it such that as I begin to type things",
"start": 4503.199,
"duration": 3.991
},
{
"text": "in then the submit button stops being",
"start": 4504.67,
"duration": 4.59
},
{
"text": "disabled disabled get set from true to",
"start": 4507.19,
"duration": 5.16
},
{
"text": "false instead and so what I really want",
"start": 4509.26,
"duration": 6.209
},
{
"text": "to do is listen for me like pressing",
"start": 4512.35,
"duration": 6.059
},
{
"text": "keys on the keyboard and so the way I",
"start": 4515.469,
"duration": 5.19
},
{
"text": "can do that is by adding yet another",
"start": 4518.409,
"duration": 5.571
},
{
"text": "event listener document query selector",
"start": 4520.659,
"duration": 5.58
},
{
"text": "what I want to add a query selector to",
"start": 4523.98,
"duration": 3.46
},
{
"text": "what do I want to add an event handler",
"start": 4526.239,
"duration": 3.391
},
{
"text": "for well I want to add an event handler",
"start": 4527.44,
"duration": 4.049
},
{
"text": "for when I type something into this",
"start": 4529.63,
"duration": 4.47
},
{
"text": "input field and this input field has an",
"start": 4531.489,
"duration": 5.4
},
{
"text": "ID of tasks so let me go ahead and get",
"start": 4534.1,
"duration": 4.59
},
{
"text": "the input field the element whose ideas",
"start": 4536.889,
"duration": 5.58
},
{
"text": "tasks and add an on key up handler on",
"start": 4538.69,
"duration": 6.36
},
{
"text": "key up again is the event when I lift my",
"start": 4542.469,
"duration": 6.27
},
{
"text": "finger off of a key go ahead and run",
"start": 4545.05,
"duration": 5.91
},
{
"text": "this function and what should the",
"start": 4548.739,
"duration": 3.811
},
{
"text": "function do well it's going to say",
"start": 4550.96,
"duration": 4.65
},
{
"text": "document query selector submit set the",
"start": 4552.55,
"duration": 5.97
},
{
"text": "disabled property equal to false",
"start": 4555.61,
"duration": 5.13
},
{
"text": "and so now here's what we're doing we're",
"start": 4558.52,
"duration": 4.02
},
{
"text": "saying by default when I first load the",
"start": 4560.74,
"duration": 4.59
},
{
"text": "page take the submit button and disable",
"start": 4562.54,
"duration": 5.55
},
{
"text": "it said dot disabled equal to true then",
"start": 4565.33,
"duration": 5.52
},
{
"text": "anytime I type a key and my finger comes",
"start": 4568.09,
"duration": 4.95
},
{
"text": "off the key that means on key up is the",
"start": 4570.85,
"duration": 4.02
},
{
"text": "event that gets triggered run this",
"start": 4573.04,
"duration": 3.69
},
{
"text": "function and what the function is going",
"start": 4574.87,
"duration": 3.99
},
{
"text": "to do is take that same submit button",
"start": 4576.73,
"duration": 4.41
},
{
"text": "and set its disabled property equal to",
"start": 4578.86,
"duration": 4.32
},
{
"text": "false so now instead of being disabled",
"start": 4581.14,
"duration": 6.54
},
{
"text": "it will be enabled so if I go back to",
"start": 4583.18,
"duration": 6.87
},
{
"text": "the page go here I type in it right now",
"start": 4587.68,
"duration": 4.2
},
{
"text": "by default the submit button is disabled",
"start": 4590.05,
"duration": 4.29
},
{
"text": "but as soon as I start typing something",
"start": 4591.88,
"duration": 4.77
},
{
"text": "now the submit button is active and I",
"start": 4594.34,
"duration": 5.4
},
{
"text": "can actually click on it and all right",
"start": 4596.65,
"duration": 4.92
},
{
"text": "this isn't great because I clicked on it",
"start": 4599.74,
"duration": 3.36
},
{
"text": "but the submit button is still enabled",
"start": 4601.57,
"duration": 3.33
},
{
"text": "so what I might like to do is all right",
"start": 4603.1,
"duration": 3.72
},
{
"text": "after I've submitted the forum after",
"start": 4604.9,
"duration": 3.84
},
{
"text": "I've added a new task let's go back and",
"start": 4606.82,
"duration": 5.0
},
{
"text": "disable the submit button so after I've",
"start": 4608.74,
"duration": 6.15
},
{
"text": "submitted the form after we've added the",
"start": 4611.82,
"duration": 5.23
},
{
"text": "new task to my list of tasks after we've",
"start": 4614.89,
"duration": 4.08
},
{
"text": "cleared out the value from the input",
"start": 4617.05,
"duration": 5.64
},
{
"text": "field let me also get the submit button",
"start": 4618.97,
"duration": 6.72
},
{
"text": "set it's disabled property equal to true",
"start": 4622.69,
"duration": 5.76
},
{
"text": "now even after I submit the form the",
"start": 4625.69,
"duration": 4.2
},
{
"text": "submit button is still going to be",
"start": 4628.45,
"duration": 3.87
},
{
"text": "disabled such that I type in foo now",
"start": 4629.89,
"duration": 4.56
},
{
"text": "submit is active I press it but the",
"start": 4632.32,
"duration": 3.39
},
{
"text": "submit button goes back to being",
"start": 4634.45,
"duration": 4.38
},
{
"text": "inactive as well it turns out that even",
"start": 4635.71,
"duration": 4.77
},
{
"text": "now there's still a little bit of a bug",
"start": 4638.83,
"duration": 2.88
},
{
"text": "if I go back here and I type in",
"start": 4640.48,
"duration": 4.44
},
{
"text": "something like bar but then I backspace",
"start": 4641.71,
"duration": 6.06
},
{
"text": "back to like nothing here the submit",
"start": 4644.92,
"duration": 4.17
},
{
"text": "button is still active so I can still",
"start": 4647.77,
"duration": 3.57
},
{
"text": "technically submit a task that has no",
"start": 4649.09,
"duration": 4.47
},
{
"text": "content inside of it and so I might like",
"start": 4651.34,
"duration": 3.9
},
{
"text": "to have some way of preventing against",
"start": 4653.56,
"duration": 3.54
},
{
"text": "that as well and that's just some",
"start": 4655.24,
"duration": 3.42
},
{
"text": "additional logic we now have access to",
"start": 4657.1,
"duration": 3.36
},
{
"text": "JavaScript that has conditions that has",
"start": 4658.66,
"duration": 4.2
},
{
"text": "loops that has functions and so if I",
"start": 4660.46,
"duration": 5.82
},
{
"text": "want to do something like conditionally",
"start": 4662.86,
"duration": 6.75
},
{
"text": "check I can say if document query",
"start": 4666.28,
"duration": 8.66
},
{
"text": "selector task dot value dot length is",
"start": 4669.61,
"duration": 8.37
},
{
"text": "greater than 0 meaning like something's",
"start": 4674.94,
"duration": 5.83
},
{
"text": "actually typed into the task field will",
"start": 4677.98,
"duration": 6.47
},
{
"text": "then go ahead and set disabled to false",
"start": 4680.77,
"duration": 7.1
},
{
"text": "but otherwise",
"start": 4684.45,
"duration": 3.42
},
{
"text": "go ahead and set disabled equal the true",
"start": 4688.69,
"duration": 6.31
},
{
"text": "so now here we're checking if the length",
"start": 4692.11,
"duration": 4.57
},
{
"text": "of what the user has typed in is greater",
"start": 4695.0,
"duration": 3.3
},
{
"text": "than zero they actually type something",
"start": 4696.68,
"duration": 3.72
},
{
"text": "in then yes give them access to the",
"start": 4698.3,
"duration": 4.53
},
{
"text": "submit button but otherwise don't give",
"start": 4700.4,
"duration": 4.83
},
{
"text": "them access to that button so now i",
"start": 4702.83,
"duration": 4.77
},
{
"text": "refresh the page disabled by default I",
"start": 4705.23,
"duration": 4.47
},
{
"text": "typed something in it's enabled I delete",
"start": 4707.6,
"duration": 4.56
},
{
"text": "delete delete and it goes back to being",
"start": 4709.7,
"duration": 4.95
},
{
"text": "disabled so javascript has allowed us to",
"start": 4712.16,
"duration": 4.11
},
{
"text": "really make our pages much more",
"start": 4714.65,
"duration": 3.45
},
{
"text": "interactive and immediately interactive",
"start": 4716.27,
"duration": 3.69
},
{
"text": "based on how the user is interacting",
"start": 4718.1,
"duration": 3.72
},
{
"text": "with the page as they begin to type",
"start": 4719.96,
"duration": 4.56
},
{
"text": "things as they begin to delete things as",
"start": 4721.82,
"duration": 4.59
},
{
"text": "they press buttons we're able to have",
"start": 4724.52,
"duration": 3.63
},
{
"text": "the page respond either by adding",
"start": 4726.41,
"duration": 3.78
},
{
"text": "content to the Dom by literally adding",
"start": 4728.15,
"duration": 4.56
},
{
"text": "parts to the HTML page of changing the",
"start": 4730.19,
"duration": 4.11
},
{
"text": "styles of things changing particular",
"start": 4732.71,
"duration": 3.42
},
{
"text": "properties of elements and this is",
"start": 4734.3,
"duration": 3.12
},
{
"text": "really where the power of JavaScript",
"start": 4736.13,
"duration": 3.3
},
{
"text": "begins to come in isn't allowing",
"start": 4737.42,
"duration": 5.52
},
{
"text": "ourselves to do things like that now so",
"start": 4739.43,
"duration": 5.31
},
{
"text": "far we've only been able to have events",
"start": 4742.94,
"duration": 4.41
},
{
"text": "happen when the user does something when",
"start": 4744.74,
"duration": 4.5
},
{
"text": "the user clicks on a button or when the",
"start": 4747.35,
"duration": 3.96
},
{
"text": "user presses a key for example but it",
"start": 4749.24,
"duration": 4.02
},
{
"text": "turns out JavaScript has other ways of",
"start": 4751.31,
"duration": 3.93
},
{
"text": "allowing functions to run in fact on",
"start": 4753.26,
"duration": 3.54
},
{
"text": "their own we can set what are called",
"start": 4755.24,
"duration": 3.27
},
{
"text": "intervals where a particular function",
"start": 4756.8,
"duration": 4.08
},
{
"text": "runs every some number of milliseconds",
"start": 4758.51,
"duration": 4.41
},
{
"text": "for example and so if we go back to like",
"start": 4760.88,
"duration": 3.8
},
{
"text": "the counter example from before right",
"start": 4762.92,
"duration": 4.89
},
{
"text": "now for this counter example I have to",
"start": 4764.68,
"duration": 4.54
},
{
"text": "be the one to press the count button",
"start": 4767.81,
"duration": 3.12
},
{
"text": "that is going to increment the value of",
"start": 4769.22,
"duration": 4.62
},
{
"text": "count every single time but I could put",
"start": 4770.93,
"duration": 5.34
},
{
"text": "that inside of an interval instead so",
"start": 4773.84,
"duration": 3.96
},
{
"text": "let me go back to counter",
"start": 4776.27,
"duration": 4.05
},
{
"text": "dot HTML whose JavaScript is inside of",
"start": 4777.8,
"duration": 6.0
},
{
"text": "counter j/s and now what I'd like to say",
"start": 4780.32,
"duration": 8.52
},
{
"text": "is I would like when the Dom content is",
"start": 4783.8,
"duration": 11.04
},
{
"text": "loaded let me set an interval for count",
"start": 4788.84,
"duration": 10.8
},
{
"text": "and 1000 so what is that going to do set",
"start": 4794.84,
"duration": 6.27
},
{
"text": "interval as a function built into",
"start": 4799.64,
"duration": 3.57
},
{
"text": "JavaScript here where I'm saying that I",
"start": 4801.11,
"duration": 3.42
},
{
"text": "would like to create a new interval",
"start": 4803.21,
"duration": 3.54
},
{
"text": "where every so often go ahead and run a",
"start": 4804.53,
"duration": 4.32
},
{
"text": "particular function and I would like to",
"start": 4806.75,
"duration": 3.9
},
{
"text": "run the count function will recall that",
"start": 4808.85,
"duration": 3.75
},
{
"text": "count function is going to increment the",
"start": 4810.65,
"duration": 3.48
},
{
"text": "value of count and I'll get rid of this",
"start": 4812.6,
"duration": 3.24
},
{
"text": "alert for now just for simplicity all I",
"start": 4814.13,
"duration": 3.87
},
{
"text": "want the count function to do is update",
"start": 4815.84,
"duration": 4.17
},
{
"text": "the h1 with the new value of the counter",
"start": 4818.0,
"duration": 2.78
},
{
"text": "and",
"start": 4820.01,
"duration": 1.91
},
{
"text": "go ahead and run that count function",
"start": 4820.78,
"duration": 3.66
},
{
"text": "every 1000 milliseconds otherwise known",
"start": 4821.92,
"duration": 5.25
},
{
"text": "as every one second go ahead and run the",
"start": 4824.44,
"duration": 5.179
},
{
"text": "count function so now when I open",
"start": 4827.17,
"duration": 6.659
},
{
"text": "counter dot HTML it's zero but every",
"start": 4829.619,
"duration": 5.741
},
{
"text": "second now it's going to change every",
"start": 4833.829,
"duration": 3.511
},
{
"text": "second updating one by one by one I",
"start": 4835.36,
"duration": 3.509
},
{
"text": "don't have to click the button of course",
"start": 4837.34,
"duration": 2.91
},
{
"text": "I could and the event handler would",
"start": 4838.869,
"duration": 3.181
},
{
"text": "still work but the interval is saying",
"start": 4840.25,
"duration": 4.829
},
{
"text": "now every one second go ahead and run",
"start": 4842.05,
"duration": 4.68
},
{
"text": "the count function and that has this",
"start": 4845.079,
"duration": 3.241
},
{
"text": "particular result so if you've ever seen",
"start": 4846.73,
"duration": 3.449
},
{
"text": "a webpage that like displays the current",
"start": 4848.32,
"duration": 3.48
},
{
"text": "time in seconds and like a countdown",
"start": 4850.179,
"duration": 3.571
},
{
"text": "timer or is displaying the current time",
"start": 4851.8,
"duration": 3.75
},
{
"text": "with seconds it might be doing something",
"start": 4853.75,
"duration": 3.15
},
{
"text": "like this just having some sort of",
"start": 4855.55,
"duration": 3.54
},
{
"text": "interval that every second is going to",
"start": 4856.9,
"duration": 4.02
},
{
"text": "count and increment in order to say",
"start": 4859.09,
"duration": 3.75
},
{
"text": "update the number to the one greater one",
"start": 4860.92,
"duration": 3.92
},
{
"text": "greater and one greater than that of",
"start": 4862.84,
"duration": 5.19
},
{
"text": "course if I close the page and go back",
"start": 4864.84,
"duration": 5.379
},
{
"text": "to it if I close these pages and then",
"start": 4868.03,
"duration": 5.279
},
{
"text": "open counter dot HTML again I've gone",
"start": 4870.219,
"duration": 5.161
},
{
"text": "back to zero like JavaScript is not",
"start": 4873.309,
"duration": 4.83
},
{
"text": "saving any state about my page it's just",
"start": 4875.38,
"duration": 5.1
},
{
"text": "every time we're running the page it's",
"start": 4878.139,
"duration": 5.131
},
{
"text": "going to go back to counter j/s it's",
"start": 4880.48,
"duration": 4.02
},
{
"text": "going to say all right we're defining a",
"start": 4883.27,
"duration": 2.82
},
{
"text": "variable called counter we're setting",
"start": 4884.5,
"duration": 3.719
},
{
"text": "that variable equal to zero so every",
"start": 4886.09,
"duration": 3.299
},
{
"text": "time I load the page it's going to be",
"start": 4888.219,
"duration": 3.57
},
{
"text": "set back to zero and that might not be",
"start": 4889.389,
"duration": 4.23
},
{
"text": "great depending on the type of page",
"start": 4891.789,
"duration": 3.301
},
{
"text": "you're trying to create that maybe you",
"start": 4893.619,
"duration": 3.571
},
{
"text": "want to page that is somehow able to",
"start": 4895.09,
"duration": 4.17
},
{
"text": "store information such that on",
"start": 4897.19,
"duration": 3.779
},
{
"text": "subsequent visits were able to utilize",
"start": 4899.26,
"duration": 3.779
},
{
"text": "the information that was already stored",
"start": 4900.969,
"duration": 4.351
},
{
"text": "some way of remembering information for",
"start": 4903.039,
"duration": 4.651
},
{
"text": "later use in later versions of",
"start": 4905.32,
"duration": 4.23
},
{
"text": "JavaScript and more modern browsers now",
"start": 4907.69,
"duration": 3.69
},
{
"text": "allow us to do something just like that",
"start": 4909.55,
"duration": 4.109
},
{
"text": "called local storage and what local",
"start": 4911.38,
"duration": 4.469
},
{
"text": "storage is is it's a way for us to be",
"start": 4913.659,
"duration": 4.471
},
{
"text": "able to store information inside of the",
"start": 4915.849,
"duration": 4.35
},
{
"text": "user's web browser that a page can ask",
"start": 4918.13,
"duration": 4.259
},
{
"text": "to store particular values inside the",
"start": 4920.199,
"duration": 4.44
},
{
"text": "web browser and later on on subsequent",
"start": 4922.389,
"duration": 4.321
},
{
"text": "visits to that page we can go back and",
"start": 4924.639,
"duration": 4.111
},
{
"text": "say let's extract those values that were",
"start": 4926.71,
"duration": 4.679
},
{
"text": "previously stored inside of local",
"start": 4928.75,
"duration": 4.98
},
{
"text": "storage local storage it's going to give",
"start": 4931.389,
"duration": 4.201
},
{
"text": "us access to two key functions that",
"start": 4933.73,
"duration": 3.3
},
{
"text": "we're going to use to manipulate this",
"start": 4935.59,
"duration": 2.129
},
{
"text": "local storage",
"start": 4937.03,
"duration": 3.72
},
{
"text": "the first is local storage getitem where",
"start": 4937.719,
"duration": 4.44
},
{
"text": "we would like to get something out of",
"start": 4940.75,
"duration": 3.869
},
{
"text": "local storage based on its key some name",
"start": 4942.159,
"duration": 4.471
},
{
"text": "that we have given to that value and we",
"start": 4944.619,
"duration": 3.96
},
{
"text": "also have access to local storage dot",
"start": 4946.63,
"duration": 4.409
},
{
"text": "set item which goes ahead and adds a new",
"start": 4948.579,
"duration": 4.261
},
{
"text": "value to local storage or replaces an",
"start": 4951.039,
"duration": 3.301
},
{
"text": "existing value in local storage",
"start": 4952.84,
"duration": 4.65
},
{
"text": "setting this key equal to a particular",
"start": 4954.34,
"duration": 5.73
},
{
"text": "value so we can use local storage then",
"start": 4957.49,
"duration": 4.83
},
{
"text": "to allow our webpages using javascript",
"start": 4960.07,
"duration": 4.2
},
{
"text": "to be able to store information and",
"start": 4962.32,
"duration": 4.02
},
{
"text": "retrieve information from the browser",
"start": 4964.27,
"duration": 4.38
},
{
"text": "and let's now try to use that in order",
"start": 4966.34,
"duration": 6.09
},
{
"text": "to solve this problem of the counter",
"start": 4968.65,
"duration": 6.05
},
{
"text": "that seems to always reset back to zero",
"start": 4972.43,
"duration": 5.01
},
{
"text": "so now in counter jeaious instead of",
"start": 4974.7,
"duration": 4.72
},
{
"text": "sending counter equal to zero the first",
"start": 4977.44,
"duration": 4.41
},
{
"text": "thing I want to know is is there already",
"start": 4979.42,
"duration": 5.22
},
{
"text": "a value for the counter in local storage",
"start": 4981.85,
"duration": 6.75
},
{
"text": "so I can ask a question like if local",
"start": 4984.64,
"duration": 8.28
},
{
"text": "storage dot get item counter meaning go",
"start": 4988.6,
"duration": 7.05
},
{
"text": "to local storage try and get the counter",
"start": 4992.92,
"duration": 5.67
},
{
"text": "and anything in this if expression will",
"start": 4995.65,
"duration": 5.34
},
{
"text": "happen if there is something inside of",
"start": 4998.59,
"duration": 4.41
},
{
"text": "local storage for counter but it turns",
"start": 5000.99,
"duration": 3.36
},
{
"text": "out that if I want to do the inverse of",
"start": 5003.0,
"duration": 3.15
},
{
"text": "that say not I can just use the",
"start": 5004.35,
"duration": 3.72
},
{
"text": "exclamation point much like in C in",
"start": 5006.15,
"duration": 3.69
},
{
"text": "JavaScript the exclamation point just",
"start": 5008.07,
"duration": 4.23
},
{
"text": "means not so meaning if there is not",
"start": 5009.84,
"duration": 4.35
},
{
"text": "something in local storage called",
"start": 5012.3,
"duration": 4.2
},
{
"text": "counter well then let's go ahead and",
"start": 5014.19,
"duration": 4.17
},
{
"text": "just set the value in local storage",
"start": 5016.5,
"duration": 5.64
},
{
"text": "local storage dot set item counter and",
"start": 5018.36,
"duration": 6.48
},
{
"text": "we'll set it equal to zero so what this",
"start": 5022.14,
"duration": 4.65
},
{
"text": "is doing here is before anything else",
"start": 5024.84,
"duration": 4.32
},
{
"text": "happens we are checking local storage to",
"start": 5026.79,
"duration": 5.09
},
{
"text": "say is there already a value for counter",
"start": 5029.16,
"duration": 5.34
},
{
"text": "and if there is not already a value for",
"start": 5031.88,
"duration": 4.21
},
{
"text": "counter we need to make sure there is",
"start": 5034.5,
"duration": 3.03
},
{
"text": "something there inside of local storage",
"start": 5036.09,
"duration": 3.09
},
{
"text": "for the counter so we are going to set",
"start": 5037.53,
"duration": 4.29
},
{
"text": "the value of counter equal to zero for",
"start": 5039.18,
"duration": 5.37
},
{
"text": "example and so now what needs to change",
"start": 5041.82,
"duration": 4.35
},
{
"text": "I'll go ahead and get rid of the",
"start": 5044.55,
"duration": 3.33
},
{
"text": "interval so that it only happens when I",
"start": 5046.17,
"duration": 3.6
},
{
"text": "click on it but what should this count",
"start": 5047.88,
"duration": 4.44
},
{
"text": "function actually do well first let me",
"start": 5049.77,
"duration": 5.37
},
{
"text": "get the value of the counter counter is",
"start": 5052.32,
"duration": 5.79
},
{
"text": "going to be whatever local storage get",
"start": 5055.14,
"duration": 5.67
},
{
"text": "item counter is I'm gonna get the",
"start": 5058.11,
"duration": 5.37
},
{
"text": "counter out of local storage I'm going",
"start": 5060.81,
"duration": 5.31
},
{
"text": "to increment it counter plus plus we'll",
"start": 5063.48,
"duration": 4.89
},
{
"text": "go ahead and set the value of this h1",
"start": 5066.12,
"duration": 3.51
},
{
"text": "elements innerhtml",
"start": 5068.37,
"duration": 3.96
},
{
"text": "equal to that counter but the last step",
"start": 5069.63,
"duration": 5.37
},
{
"text": "is I'll also do local storage dot set",
"start": 5072.33,
"duration": 6.36
},
{
"text": "item counter is equal to the new value",
"start": 5075.0,
"duration": 7.29
},
{
"text": "of counter so what I've done here is to",
"start": 5078.69,
"duration": 5.73
},
{
"text": "say that when I click the button count",
"start": 5082.29,
"duration": 3.93
},
{
"text": "function is going to run we're first",
"start": 5084.42,
"duration": 3.84
},
{
"text": "going to go into local storage get",
"start": 5086.22,
"duration": 4.5
},
{
"text": "value for the key counter whatever the",
"start": 5088.26,
"duration": 4.35
},
{
"text": "value of counter happens to be save it",
"start": 5090.72,
"duration": 3.27
},
{
"text": "inside of this variable called counter",
"start": 5092.61,
"duration": 3.03
},
{
"text": "we'll go ahead and increment that",
"start": 5093.99,
"duration": 3.54
},
{
"text": "variable setting it equal to itself plus",
"start": 5095.64,
"duration": 5.07
},
{
"text": "one update the h1s innerhtml same as",
"start": 5097.53,
"duration": 4.56
},
{
"text": "before just to update what we actually",
"start": 5100.71,
"duration": 4.38
},
{
"text": "see on the page but then go ahead and",
"start": 5102.09,
"duration": 6.15
},
{
"text": "local storage set item counter gets set",
"start": 5105.09,
"duration": 8.13
},
{
"text": "to counter for example so now let's go",
"start": 5108.24,
"duration": 9.15
},
{
"text": "ahead and see what's going to happen if",
"start": 5113.22,
"duration": 7.44
},
{
"text": "I go ahead and open counter dot HTML we",
"start": 5117.39,
"duration": 7.71
},
{
"text": "see 0 we count 1 2 3 4 5 everything so",
"start": 5120.66,
"duration": 6.54
},
{
"text": "far so good now watch what happens if i",
"start": 5125.1,
"duration": 5.15
},
{
"text": "refresh this page i refresh the page and",
"start": 5127.2,
"duration": 4.95
},
{
"text": "alright that seems a little bit strange",
"start": 5130.25,
"duration": 4.42
},
{
"text": "at 0 let me try counting and see what",
"start": 5132.15,
"duration": 4.77
},
{
"text": "happens i press count and alright the",
"start": 5134.67,
"duration": 4.8
},
{
"text": "count changed to 6 so it seems like it",
"start": 5136.92,
"duration": 4.56
},
{
"text": "did remember that i counted up to 5 0 1",
"start": 5139.47,
"duration": 4.23
},
{
"text": "2 3 4 5 but when i refresh the page it",
"start": 5141.48,
"duration": 4.38
},
{
"text": "still showed me 0 but then let me count",
"start": 5143.7,
"duration": 3.6
},
{
"text": "up to the number 6 and I can keep",
"start": 5145.86,
"duration": 3.78
},
{
"text": "counting 7 8 9 10 what happens if i",
"start": 5147.3,
"duration": 3.93
},
{
"text": "refresh the page now I can try it i",
"start": 5149.64,
"duration": 4.77
},
{
"text": "refresh the page I've gone back to 0 but",
"start": 5151.23,
"duration": 5.25
},
{
"text": "I count and okay now I'm at 11 so",
"start": 5154.41,
"duration": 3.96
},
{
"text": "somehow I am still remembering but the",
"start": 5156.48,
"duration": 3.6
},
{
"text": "first time it's still giving me 0 every",
"start": 5158.37,
"duration": 4.5
},
{
"text": "time why might that be well if you look",
"start": 5160.08,
"duration": 5.01
},
{
"text": "back at counter dot HTML you'll notice",
"start": 5162.87,
"duration": 3.87
},
{
"text": "that the reason is just inside the body",
"start": 5165.09,
"duration": 3.81
},
{
"text": "of the page the initial value of the h1",
"start": 5166.74,
"duration": 4.5
},
{
"text": "is just always 0 so if I want to fix",
"start": 5168.9,
"duration": 4.26
},
{
"text": "that then what I need the same is when",
"start": 5171.24,
"duration": 4.11
},
{
"text": "the Dom content is loaded go ahead and",
"start": 5173.16,
"duration": 5.97
},
{
"text": "get document query selector h1 go ahead",
"start": 5175.35,
"duration": 5.34
},
{
"text": "and update the innerhtml",
"start": 5179.13,
"duration": 6.68
},
{
"text": "equal to whatever local storage get item",
"start": 5180.69,
"duration": 8.16
},
{
"text": "counter happens to be so every time I",
"start": 5185.81,
"duration": 5.17
},
{
"text": "open the page even before I click the",
"start": 5188.85,
"duration": 3.87
},
{
"text": "button even before the event listener is",
"start": 5190.98,
"duration": 3.6
},
{
"text": "triggered I'd like to say go ahead and",
"start": 5192.72,
"duration": 3.78
},
{
"text": "replace this heading update its inner",
"start": 5194.58,
"duration": 4.95
},
{
"text": "HTML to be the result of getting the",
"start": 5196.5,
"duration": 5.54
},
{
"text": "counter out of local storage for example",
"start": 5199.53,
"duration": 5.76
},
{
"text": "so now for refresh the page it's all at",
"start": 5202.04,
"duration": 5.38
},
{
"text": "11 I can update update update click",
"start": 5205.29,
"duration": 4.32
},
{
"text": "again some number of times bring it up",
"start": 5207.42,
"duration": 4.47
},
{
"text": "to 18 for example refresh the page and",
"start": 5209.61,
"duration": 4.35
},
{
"text": "it stays at the number 18 and no matter",
"start": 5211.89,
"duration": 3.72
},
{
"text": "what value I get it to it's going to",
"start": 5213.96,
"duration": 3.27
},
{
"text": "store that number inside of local",
"start": 5215.61,
"duration": 3.51
},
{
"text": "storage such that when i refresh the",
"start": 5217.23,
"duration": 4.349
},
{
"text": "page that number is going to stay there",
"start": 5219.12,
"duration": 4.229
},
{
"text": "we can actually see the value inside of",
"start": 5221.579,
"duration": 3.721
},
{
"text": "local storage but again going into",
"start": 5223.349,
"duration": 4.98
},
{
"text": "Chrome's inspector I go into Chrome if I",
"start": 5225.3,
"duration": 6.419
},
{
"text": "go to the application tab and I go to",
"start": 5228.329,
"duration": 6.3
},
{
"text": "local storage here on the Left I can see",
"start": 5231.719,
"duration": 4.47
},
{
"text": "that I have a value for key counter",
"start": 5234.629,
"duration": 3.48
},
{
"text": "whose value in this case happens to be",
"start": 5236.189,
"duration": 3.54
},
{
"text": "28 and you could go into local storage",
"start": 5238.109,
"duration": 3.27
},
{
"text": "you can manipulate this value you could",
"start": 5239.729,
"duration": 3.27
},
{
"text": "delete it if you want but this just goes",
"start": 5241.379,
"duration": 3.12
},
{
"text": "to show you that we have now stored this",
"start": 5242.999,
"duration": 4.41
},
{
"text": "value inside of my browser such that on",
"start": 5244.499,
"duration": 4.68
},
{
"text": "subsequent visits if this page gets",
"start": 5247.409,
"duration": 3.81
},
{
"text": "loaded again we can access that value",
"start": 5249.179,
"duration": 4.55
},
{
"text": "from inside of the application as well",
"start": 5251.219,
"duration": 5.07
},
{
"text": "and so now we've been able to see how",
"start": 5253.729,
"duration": 4.45
},
{
"text": "our pages are able to store data in",
"start": 5256.289,
"duration": 3.84
},
{
"text": "order to just make the user experience a",
"start": 5258.179,
"duration": 3.42
},
{
"text": "little bit better if we want the user to",
"start": 5260.129,
"duration": 3.39
},
{
"text": "be able to have information remembered",
"start": 5261.599,
"duration": 3.9
},
{
"text": "from the last time they visited a",
"start": 5263.519,
"duration": 3.33
},
{
"text": "particular page we can sometimes",
"start": 5265.499,
"duration": 5.04
},
{
"text": "actually be quite helpful all right so",
"start": 5266.849,
"duration": 4.92
},
{
"text": "now we've seen a lot of features of",
"start": 5270.539,
"duration": 3.0
},
{
"text": "JavaScript we've seen a bunch of",
"start": 5271.769,
"duration": 3.301
},
{
"text": "different ways of representing data we",
"start": 5273.539,
"duration": 3.39
},
{
"text": "store data in variables and those",
"start": 5275.07,
"duration": 3.48
},
{
"text": "variables have had types like integers",
"start": 5276.929,
"duration": 3.9
},
{
"text": "those variables of sum has been strings",
"start": 5278.55,
"duration": 4.409
},
{
"text": "and some times have been HTML elements",
"start": 5280.829,
"duration": 4.471
},
{
"text": "sometimes they've been arrays or lists",
"start": 5282.959,
"duration": 4.051
},
{
"text": "of our items sometimes they've even been",
"start": 5285.3,
"duration": 3.359
},
{
"text": "functions so we can set a variable equal",
"start": 5287.01,
"duration": 3.569
},
{
"text": "to a function but perhaps one of the",
"start": 5288.659,
"duration": 4.32
},
{
"text": "most useful data types inside of",
"start": 5290.579,
"duration": 5.73
},
{
"text": "JavaScript is the JavaScript object so",
"start": 5292.979,
"duration": 4.801
},
{
"text": "go into the JavaScript console just to",
"start": 5296.309,
"duration": 3.451
},
{
"text": "demonstrate this what the JavaScript",
"start": 5297.78,
"duration": 4.529
},
{
"text": "object is is it's really the equivalent",
"start": 5299.76,
"duration": 4.799
},
{
"text": "of like a Python dictionary some",
"start": 5302.309,
"duration": 5.07
},
{
"text": "Association of keys to values where you",
"start": 5304.559,
"duration": 4.44
},
{
"text": "can look up something by a key or by a",
"start": 5307.379,
"duration": 4.651
},
{
"text": "property and see what his value happens",
"start": 5308.999,
"duration": 6.0
},
{
"text": "to be so if I had a variable like person",
"start": 5312.03,
"duration": 5.909
},
{
"text": "I could set person equal to a JavaScript",
"start": 5314.999,
"duration": 6.42
},
{
"text": "object who's like first name is Harry",
"start": 5317.939,
"duration": 7.65
},
{
"text": "and whose last name is Potter again",
"start": 5321.419,
"duration": 6.93
},
{
"text": "using syntax very similar to what the",
"start": 5325.589,
"duration": 5.04
},
{
"text": "dictionary syntax looks like inside of",
"start": 5328.349,
"duration": 4.86
},
{
"text": "Python as well and now that I have this",
"start": 5330.629,
"duration": 5.01
},
{
"text": "variable person which is first Harry",
"start": 5333.209,
"duration": 4.95
},
{
"text": "last Potter I can access a particular",
"start": 5335.639,
"duration": 4.08
},
{
"text": "property of the person in a number of",
"start": 5338.159,
"duration": 3.51
},
{
"text": "ways I can say something like person dot",
"start": 5339.719,
"duration": 3.78
},
{
"text": "first to say get me the first name",
"start": 5341.669,
"duration": 4.56
},
{
"text": "property of this particular object and I",
"start": 5343.499,
"duration": 4.59
},
{
"text": "see that it's equal to Harry I could",
"start": 5346.229,
"duration": 3.66
},
{
"text": "equivalently use square bracket notation",
"start": 5348.089,
"duration": 3.961
},
{
"text": "the way Python does square bracket first",
"start": 5349.889,
"duration": 4.29
},
{
"text": "and that will also give me Harry",
"start": 5352.05,
"duration": 4.53
},
{
"text": "but this turns out to be quite powerful",
"start": 5354.179,
"duration": 4.741
},
{
"text": "to be able to represent data in this",
"start": 5356.58,
"duration": 4.23
},
{
"text": "structured way like this where I have an",
"start": 5358.92,
"duration": 3.63
},
{
"text": "association of keys or otherwise known",
"start": 5360.81,
"duration": 4.11
},
{
"text": "as properties with particular values and",
"start": 5362.55,
"duration": 4.02
},
{
"text": "then I have the ability given a",
"start": 5364.92,
"duration": 4.23
},
{
"text": "JavaScript object to be able to access a",
"start": 5366.57,
"duration": 4.68
},
{
"text": "particular value and it turns out that",
"start": 5369.15,
"duration": 3.93
},
{
"text": "one of the ways this is most useful is",
"start": 5371.25,
"duration": 4.14
},
{
"text": "in the exchange of data moving data",
"start": 5373.08,
"duration": 5.07
},
{
"text": "around from one service to another and",
"start": 5375.39,
"duration": 4.65
},
{
"text": "so here we're going to introduce what",
"start": 5378.15,
"duration": 3.81
},
{
"text": "are known as api's otherwise known as",
"start": 5380.04,
"duration": 4.26
},
{
"text": "application programming interfaces which",
"start": 5381.96,
"duration": 4.41
},
{
"text": "in the context of the web you can think",
"start": 5384.3,
"duration": 4.14
},
{
"text": "of as some well-defined structured way",
"start": 5386.37,
"duration": 4.26
},
{
"text": "for services on the Internet to",
"start": 5388.44,
"duration": 4.11
},
{
"text": "communicate with each other that if you",
"start": 5390.63,
"duration": 4.02
},
{
"text": "want your application to be able to talk",
"start": 5392.55,
"duration": 3.899
},
{
"text": "to some other service maybe you want",
"start": 5394.65,
"duration": 3.72
},
{
"text": "your application to interact with Google",
"start": 5396.449,
"duration": 3.361
},
{
"text": "Maps or to be able to interact with",
"start": 5398.37,
"duration": 3.3
},
{
"text": "Amazon or some other weather service to",
"start": 5399.81,
"duration": 3.48
},
{
"text": "get the day's weather then you might be",
"start": 5401.67,
"duration": 4.23
},
{
"text": "able to access some API some mechanism",
"start": 5403.29,
"duration": 4.409
},
{
"text": "whereby you can communicate with another",
"start": 5405.9,
"duration": 3.72
},
{
"text": "service by sending a request and",
"start": 5407.699,
"duration": 4.351
},
{
"text": "receiving back data in some sort of very",
"start": 5409.62,
"duration": 4.89
},
{
"text": "well structured format and very often",
"start": 5412.05,
"duration": 4.56
},
{
"text": "that well structured format happens to",
"start": 5414.51,
"duration": 4.05
},
{
"text": "be a particular type of data known as",
"start": 5416.61,
"duration": 3.96
},
{
"text": "Jason which stands for JavaScript object",
"start": 5418.56,
"duration": 4.679
},
{
"text": "notation which is a way of transferring",
"start": 5420.57,
"duration": 6.0
},
{
"text": "data in the form of JavaScript objects",
"start": 5423.239,
"duration": 5.611
},
{
"text": "these sort of objects that happen to",
"start": 5426.57,
"duration": 4.47
},
{
"text": "have properties and values associated",
"start": 5428.85,
"duration": 4.74
},
{
"text": "with them and so what does javascript",
"start": 5431.04,
"duration": 4.29
},
{
"text": "object notation look like well if we",
"start": 5433.59,
"duration": 3.0
},
{
"text": "think back to the applications that",
"start": 5435.33,
"duration": 2.67
},
{
"text": "we've been creating these applications",
"start": 5436.59,
"duration": 2.97
},
{
"text": "that are able to represent things like",
"start": 5438.0,
"duration": 4.17
},
{
"text": "an airline and many movements of planes",
"start": 5439.56,
"duration": 4.38
},
{
"text": "between particular destinations a",
"start": 5442.17,
"duration": 4.41
},
{
"text": "JavaScript object representing a flight",
"start": 5443.94,
"duration": 4.32
},
{
"text": "might look something like this",
"start": 5446.58,
"duration": 3.48
},
{
"text": "a JavaScript object that has properties",
"start": 5448.26,
"duration": 4.74
},
{
"text": "for origin is something destination is",
"start": 5450.06,
"duration": 4.889
},
{
"text": "something duration is something things",
"start": 5453.0,
"duration": 3.84
},
{
"text": "we've seen before but you might imagine",
"start": 5454.949,
"duration": 4.02
},
{
"text": "that if we wanted our airline to be able",
"start": 5456.84,
"duration": 3.87
},
{
"text": "to make its data available to other",
"start": 5458.969,
"duration": 3.811
},
{
"text": "services so that other web applications",
"start": 5460.71,
"duration": 4.35
},
{
"text": "or other programs could programmatically",
"start": 5462.78,
"duration": 4.5
},
{
"text": "access information about flights we",
"start": 5465.06,
"duration": 5.07
},
{
"text": "could pass data in this format to those",
"start": 5467.28,
"duration": 5.01
},
{
"text": "other applications so that they could",
"start": 5470.13,
"duration": 3.779
},
{
"text": "then treat this as a JavaScript object",
"start": 5472.29,
"duration": 3.84
},
{
"text": "and get access to the information about",
"start": 5473.909,
"duration": 3.631
},
{
"text": "it and the nice thing about this",
"start": 5476.13,
"duration": 3.839
},
{
"text": "particular representation is that it is",
"start": 5477.54,
"duration": 4.86
},
{
"text": "both human readable and machine readable",
"start": 5479.969,
"duration": 4.17
},
{
"text": "that we as people can look at this and",
"start": 5482.4,
"duration": 3.48
},
{
"text": "get an intuitive understanding for what",
"start": 5484.139,
"duration": 3.901
},
{
"text": "all of this means but also a computer",
"start": 5485.88,
"duration": 3.84
},
{
"text": "knows how to access particular",
"start": 5488.04,
"duration": 3.18
},
{
"text": "properties that appear before the colon",
"start": 5489.72,
"duration": 3.96
},
{
"text": "and get access to what those values are",
"start": 5491.22,
"duration": 5.67
},
{
"text": "which appear after that colon as well so",
"start": 5493.68,
"duration": 5.25
},
{
"text": "JavaScript object notation otherwise",
"start": 5496.89,
"duration": 4.2
},
{
"text": "known as jason offers a very convenient",
"start": 5498.93,
"duration": 4.08
},
{
"text": "representation and this isn't exactly",
"start": 5501.09,
"duration": 4.8
},
{
"text": "what the JavaScript object syntax is in",
"start": 5503.01,
"duration": 4.5
},
{
"text": "JavaScript objects you don't strictly",
"start": 5505.89,
"duration": 3.3
},
{
"text": "need the quotation marks around the keys",
"start": 5507.51,
"duration": 3.66
},
{
"text": "you could just say origin colon and not",
"start": 5509.19,
"duration": 4.11
},
{
"text": "origin in quotation marks so JavaScript",
"start": 5511.17,
"duration": 4.35
},
{
"text": "object notation uses slightly different",
"start": 5513.3,
"duration": 4.44
},
{
"text": "syntax but ultimately very reminiscent",
"start": 5515.52,
"duration": 3.93
},
{
"text": "what we've seen in JavaScript objects",
"start": 5517.74,
"duration": 3.81
},
{
"text": "and JavaScript knows how to take data in",
"start": 5519.45,
"duration": 3.99
},
{
"text": "this form and turn it into something",
"start": 5521.55,
"duration": 3.81
},
{
"text": "like a JavaScript object and turns out",
"start": 5523.44,
"duration": 3.42
},
{
"text": "there ways of doing this in Python as",
"start": 5525.36,
"duration": 3.09
},
{
"text": "well in other programming languages have",
"start": 5526.86,
"duration": 4.41
},
{
"text": "the ability to interpret JSON data in",
"start": 5528.45,
"duration": 4.89
},
{
"text": "order to use it in some meaningful way",
"start": 5531.27,
"duration": 4.44
},
{
"text": "and another advantage of the JSON",
"start": 5533.34,
"duration": 4.38
},
{
"text": "representation is it is very conducive",
"start": 5535.71,
"duration": 4.5
},
{
"text": "to representing structures of things so",
"start": 5537.72,
"duration": 4.2
},
{
"text": "these values don't just need to be",
"start": 5540.21,
"duration": 4.38
},
{
"text": "strings or numbers they could be lists",
"start": 5541.92,
"duration": 4.44
},
{
"text": "or arrays that happen have a sequence of",
"start": 5544.59,
"duration": 3.96
},
{
"text": "possible values or they could even be",
"start": 5546.36,
"duration": 4.29
},
{
"text": "other javascript objects that if we",
"start": 5548.55,
"duration": 4.2
},
{
"text": "wanted to represent not just a city name",
"start": 5550.65,
"duration": 4.23
},
{
"text": "but represent the city name and the",
"start": 5552.75,
"duration": 4.02
},
{
"text": "airport code for example as we saw that",
"start": 5554.88,
"duration": 4.08
},
{
"text": "we wanted to do before I could instead",
"start": 5556.77,
"duration": 4.2
},
{
"text": "of having origin be equal to a string",
"start": 5558.96,
"duration": 4.56
},
{
"text": "like New York have origin be equal to",
"start": 5560.97,
"duration": 5.01
},
{
"text": "yet another JavaScript object that",
"start": 5563.52,
"duration": 4.89
},
{
"text": "contains a city property and a code",
"start": 5565.98,
"duration": 3.78
},
{
"text": "property where the city is the name of",
"start": 5568.41,
"duration": 3.57
},
{
"text": "the city and the code is the name of the",
"start": 5569.76,
"duration": 3.96
},
{
"text": "airport code and the important thing is",
"start": 5571.98,
"duration": 3.54
},
{
"text": "as long as I and the person I'm",
"start": 5573.72,
"duration": 3.66
},
{
"text": "communicating with agree upon this",
"start": 5575.52,
"duration": 3.99
},
{
"text": "representation agree upon what the names",
"start": 5577.38,
"duration": 4.11
},
{
"text": "of these keys are and what the structure",
"start": 5579.51,
"duration": 4.74
},
{
"text": "of this JSON payload this JSON object",
"start": 5581.49,
"duration": 5.04
},
{
"text": "happens to be then the person on the",
"start": 5584.25,
"duration": 4.2
},
{
"text": "receiving end can take this data and",
"start": 5586.53,
"duration": 3.6
},
{
"text": "write a program that's able to interpret",
"start": 5588.45,
"duration": 3.63
},
{
"text": "it and use that data in some meaningful",
"start": 5590.13,
"duration": 4.23
},
{
"text": "way and so we'll see an example of this",
"start": 5592.08,
"duration": 4.41
},
{
"text": "now of using javascript to be able to",
"start": 5594.36,
"duration": 3.51
},
{
"text": "communicate with yet another online",
"start": 5596.49,
"duration": 3.93
},
{
"text": "service in particular for accessing",
"start": 5597.87,
"duration": 4.8
},
{
"text": "information about currency exchange",
"start": 5600.42,
"duration": 3.78
},
{
"text": "rates currency exchange rates are always",
"start": 5602.67,
"duration": 3.36
},
{
"text": "changing we want access to the latest",
"start": 5604.2,
"duration": 4.2
},
{
"text": "currency exchange rate data and if there",
"start": 5606.03,
"duration": 4.32
},
{
"text": "is an online service an API that",
"start": 5608.4,
"duration": 4.14
},
{
"text": "provides access to that data in JSON",
"start": 5610.35,
"duration": 4.11
},
{
"text": "form in a format like this that is",
"start": 5612.54,
"duration": 3.87
},
{
"text": "machine readable then we can use that",
"start": 5614.46,
"duration": 4.77
},
{
"text": "data to write a stock a currency",
"start": 5616.41,
"duration": 5.16
},
{
"text": "exchange application that uses real time",
"start": 5619.23,
"duration": 2.88
},
{
"text": "data",
"start": 5621.57,
"duration": 2.79
},
{
"text": "in order to make those conversions what",
"start": 5622.11,
"duration": 3.839
},
{
"text": "might that data look like well the data",
"start": 5624.36,
"duration": 3.449
},
{
"text": "could look something like this that we",
"start": 5625.949,
"duration": 3.841
},
{
"text": "make a request for accessing what are",
"start": 5627.809,
"duration": 3.81
},
{
"text": "the exchange rates for converting from",
"start": 5629.79,
"duration": 4.17
},
{
"text": "US dollars of the West Newton is USD and",
"start": 5631.619,
"duration": 4.951
},
{
"text": "we get back a JSON object that looks",
"start": 5633.96,
"duration": 5.79
},
{
"text": "like this and it has a base key of USD",
"start": 5636.57,
"duration": 5.549
},
{
"text": "and then has a rates key that has a",
"start": 5639.75,
"duration": 3.659
},
{
"text": "whole bunch of rates within it so",
"start": 5642.119,
"duration": 2.881
},
{
"text": "conversion to euros and Japanese yen",
"start": 5643.409,
"duration": 4.051
},
{
"text": "great british britain pounds as well as",
"start": 5645.0,
"duration": 4.079
},
{
"text": "Australian dollars and all of the",
"start": 5647.46,
"duration": 3.06
},
{
"text": "various different currency exchange",
"start": 5649.079,
"duration": 2.58
},
{
"text": "rates for all of these different",
"start": 5650.52,
"duration": 3.659
},
{
"text": "currencies for example and this doesn't",
"start": 5651.659,
"duration": 4.351
},
{
"text": "have to be the way that this data is",
"start": 5654.179,
"duration": 3.121
},
{
"text": "structured but it happens to be a",
"start": 5656.01,
"duration": 3.33
},
{
"text": "convenient way and so long as the person",
"start": 5657.3,
"duration": 4.68
},
{
"text": "providing this data to me and I both",
"start": 5659.34,
"duration": 4.649
},
{
"text": "know what this structure is we can begin",
"start": 5661.98,
"duration": 3.929
},
{
"text": "to write programs that are able to use",
"start": 5663.989,
"duration": 3.9
},
{
"text": "that data and so will now see our",
"start": 5665.909,
"duration": 6.301
},
{
"text": "example of an API which is exchange",
"start": 5667.889,
"duration": 7.951
},
{
"text": "rates API I owe and if we go to API dot",
"start": 5672.21,
"duration": 6.21
},
{
"text": "exchange rates API am / latest and",
"start": 5675.84,
"duration": 5.069
},
{
"text": "provide a get parameter of base equals",
"start": 5678.42,
"duration": 6.09
},
{
"text": "US dollars then what we get back is data",
"start": 5680.909,
"duration": 4.851
},
{
"text": "that looks like this",
"start": 5684.51,
"duration": 3.45
},
{
"text": "now it's a little bit messy looking not",
"start": 5685.76,
"duration": 4.12
},
{
"text": "nearly as clean as we saw before but",
"start": 5687.96,
"duration": 3.63
},
{
"text": "it's the same exact thing just without",
"start": 5689.88,
"duration": 3.239
},
{
"text": "the whitespace we have a JavaScript",
"start": 5691.59,
"duration": 4.259
},
{
"text": "object that has a rates key that tells",
"start": 5693.119,
"duration": 4.891
},
{
"text": "me all right here is the exchange rate",
"start": 5695.849,
"duration": 4.801
},
{
"text": "between US Dollars and Canadian dollars",
"start": 5698.01,
"duration": 4.2
},
{
"text": "in the pound in the euro and other",
"start": 5700.65,
"duration": 3.839
},
{
"text": "currencies that exist as well and down",
"start": 5702.21,
"duration": 4.02
},
{
"text": "below we have the base of what base",
"start": 5704.489,
"duration": 4.17
},
{
"text": "currency we're converting from so all of",
"start": 5706.23,
"duration": 4.8
},
{
"text": "this data can come back to me if I just",
"start": 5708.659,
"duration": 4.381
},
{
"text": "make an HTTP request I make a web",
"start": 5711.03,
"duration": 4.919
},
{
"text": "request to this particular URL I then",
"start": 5713.04,
"duration": 5.22
},
{
"text": "get access to all of this currency",
"start": 5715.949,
"duration": 4.561
},
{
"text": "exchange rate information that I can",
"start": 5718.26,
"duration": 5.16
},
{
"text": "then use inside of my application so how",
"start": 5720.51,
"duration": 4.74
},
{
"text": "can I do this how can I now begin to use",
"start": 5723.42,
"duration": 4.17
},
{
"text": "this information inside of an",
"start": 5725.25,
"duration": 4.8
},
{
"text": "application let's now create a new page",
"start": 5727.59,
"duration": 7.109
},
{
"text": "I'm gonna call this currency HTML inside",
"start": 5730.05,
"duration": 9.359
},
{
"text": "of currency about HTML at our usual HTML",
"start": 5734.699,
"duration": 8.88
},
{
"text": "a title of currency exchange and a body",
"start": 5739.409,
"duration": 7.23
},
{
"text": "and inside the body and we're just going",
"start": 5743.579,
"duration": 4.921
},
{
"text": "to include nothing for now what I really",
"start": 5746.639,
"duration": 3.721
},
{
"text": "care about is the JavaScript that is",
"start": 5748.5,
"duration": 4.53
},
{
"text": "going to make a web request in order to",
"start": 5750.36,
"duration": 5.1
},
{
"text": "get access to additional data",
"start": 5753.03,
"duration": 4.83
},
{
"text": "so far in JavaScript our JavaScript code",
"start": 5755.46,
"duration": 4.77
},
{
"text": "has exclusively been running code that",
"start": 5757.86,
"duration": 5.28
},
{
"text": "exists only on our computer it's running",
"start": 5760.23,
"duration": 4.739
},
{
"text": "inside the web browser and all happening",
"start": 5763.14,
"duration": 3.21
},
{
"text": "inside the web browser we're not",
"start": 5764.969,
"duration": 2.941
},
{
"text": "communicating with some external server",
"start": 5766.35,
"duration": 3.33
},
{
"text": "what we'll take a look at now is",
"start": 5767.91,
"duration": 3.75
},
{
"text": "something known as Ajax which was about",
"start": 5769.68,
"duration": 3.87
},
{
"text": "asynchronous JavaScript where the idea",
"start": 5771.66,
"duration": 4.02
},
{
"text": "is that even after a page has loaded",
"start": 5773.55,
"duration": 5.189
},
{
"text": "using JavaScript we can make additional",
"start": 5775.68,
"duration": 4.92
},
{
"text": "web requests to ask for additional",
"start": 5778.739,
"duration": 4.051
},
{
"text": "information either from our own web",
"start": 5780.6,
"duration": 3.9
},
{
"text": "servers or from some third party web",
"start": 5782.79,
"duration": 3.69
},
{
"text": "servers if we want additional",
"start": 5784.5,
"duration": 4.41
},
{
"text": "information on our page and what we want",
"start": 5786.48,
"duration": 4.41
},
{
"text": "in this case is for our page to make an",
"start": 5788.91,
"duration": 4.26
},
{
"text": "asynchronous request to request for",
"start": 5790.89,
"duration": 4.71
},
{
"text": "additional data about the current",
"start": 5793.17,
"duration": 5.88
},
{
"text": "currency exchange rates for example so",
"start": 5795.6,
"duration": 5.25
},
{
"text": "how am I going to do that well I want to",
"start": 5799.05,
"duration": 6.86
},
{
"text": "do this after the Dom content is loaded",
"start": 5800.85,
"duration": 8.639
},
{
"text": "so we'll add that usually there and what",
"start": 5805.91,
"duration": 4.75
},
{
"text": "we're going to take advantage of as a",
"start": 5809.489,
"duration": 2.521
},
{
"text": "function built-in to more recent",
"start": 5810.66,
"duration": 2.82
},
{
"text": "versions of JavaScript and supported by",
"start": 5812.01,
"duration": 3.45
},
{
"text": "most major browsers now and if the",
"start": 5813.48,
"duration": 4.56
},
{
"text": "function called fetch and what fetch is",
"start": 5815.46,
"duration": 4.56
},
{
"text": "going to do is it is going to make a web",
"start": 5818.04,
"duration": 4.02
},
{
"text": "request it is going to query some",
"start": 5820.02,
"duration": 3.48
},
{
"text": "website it could be our own it could be",
"start": 5822.06,
"duration": 3.36
},
{
"text": "someone else's and it's gonna get back",
"start": 5823.5,
"duration": 5.13
},
{
"text": "some HTTP response from that page and",
"start": 5825.42,
"duration": 5.28
},
{
"text": "I'm going to fetch in the page I'm going",
"start": 5828.63,
"duration": 6.03
},
{
"text": "to fetch is this URL API not exchange",
"start": 5830.7,
"duration": 6.57
},
{
"text": "rates API dot io / latest base equals",
"start": 5834.66,
"duration": 4.68
},
{
"text": "USD and the only reason I happen to know",
"start": 5837.27,
"duration": 3.78
},
{
"text": "how this API works is because I've read",
"start": 5839.34,
"duration": 3.93
},
{
"text": "the api's documentation that describes",
"start": 5841.05,
"duration": 4.59
},
{
"text": "how the URL parameters work and what the",
"start": 5843.27,
"duration": 3.66
},
{
"text": "structure of the data that I get back",
"start": 5845.64,
"duration": 4.17
},
{
"text": "isn't and so I'm here going to say go",
"start": 5846.93,
"duration": 5.16
},
{
"text": "ahead and fetch from this URL make a",
"start": 5849.81,
"duration": 4.62
},
{
"text": "HTTP request asking for additional",
"start": 5852.09,
"duration": 5.43
},
{
"text": "information from this URL and get back",
"start": 5854.43,
"duration": 4.95
},
{
"text": "what the results are going to be and",
"start": 5857.52,
"duration": 4.68
},
{
"text": "what fetch gives back to us is something",
"start": 5859.38,
"duration": 5.28
},
{
"text": "in JavaScript known as a promise and a",
"start": 5862.2,
"duration": 3.96
},
{
"text": "promise is going to be a way of",
"start": 5864.66,
"duration": 3.96
},
{
"text": "representing the idea that something is",
"start": 5866.16,
"duration": 4.2
},
{
"text": "going to come back but it may not come",
"start": 5868.62,
"duration": 3.69
},
{
"text": "back immediately we're not going to go",
"start": 5870.36,
"duration": 3.33
},
{
"text": "into the details of exactly how those",
"start": 5872.31,
"duration": 3.15
},
{
"text": "promises work but it turns out there's a",
"start": 5873.69,
"duration": 3.45
},
{
"text": "particular syntax for dealing with them",
"start": 5875.46,
"duration": 4.14
},
{
"text": "which is that I can say after I fetch I",
"start": 5877.14,
"duration": 6.45
},
{
"text": "can add a line called dot then that says",
"start": 5879.6,
"duration": 5.85
},
{
"text": "what should I do when the promise comes",
"start": 5883.59,
"duration": 4.26
},
{
"text": "back once I get back something like a",
"start": 5885.45,
"duration": 3.84
},
{
"text": "response",
"start": 5887.85,
"duration": 3.39
},
{
"text": "and so when I get back the response what",
"start": 5889.29,
"duration": 3.93
},
{
"text": "I want to do is convert the response",
"start": 5891.24,
"duration": 5.22
},
{
"text": "into Jason treat it as Jason data Java a",
"start": 5893.22,
"duration": 5.19
},
{
"text": "JavaScript object as something that I",
"start": 5896.46,
"duration": 3.96
},
{
"text": "can then manipulate and so what I can do",
"start": 5898.41,
"duration": 4.32
},
{
"text": "is just use this as a function to say go",
"start": 5900.42,
"duration": 8.04
},
{
"text": "ahead and return response Jason and so",
"start": 5902.73,
"duration": 7.68
},
{
"text": "what this is saying is go ahead and get",
"start": 5908.46,
"duration": 4.5
},
{
"text": "me the latest exchange rates and then",
"start": 5910.41,
"duration": 4.2
},
{
"text": "after that's done this is an",
"start": 5912.96,
"duration": 3.18
},
{
"text": "asynchronous process it might take some",
"start": 5914.61,
"duration": 3.78
},
{
"text": "time but once I get back those results",
"start": 5916.14,
"duration": 4.89
},
{
"text": "then run this function take the response",
"start": 5918.39,
"duration": 5.52
},
{
"text": "and return the jason version of the",
"start": 5921.03,
"duration": 4.98
},
{
"text": "response convert that response into just",
"start": 5923.91,
"duration": 4.5
},
{
"text": "the raw JSON data such that I can use",
"start": 5926.01,
"duration": 4.32
},
{
"text": "that data to then access the currency",
"start": 5928.41,
"duration": 3.96
},
{
"text": "exchange rates and it turns out that",
"start": 5930.33,
"duration": 3.81
},
{
"text": "with arrow functions if you ever have a",
"start": 5932.37,
"duration": 3.42
},
{
"text": "very simple function that all it's doing",
"start": 5934.14,
"duration": 3.57
},
{
"text": "is taking something and returning",
"start": 5935.79,
"duration": 4.17
},
{
"text": "something else I can simplify this",
"start": 5937.71,
"duration": 4.86
},
{
"text": "function even further and just say I can",
"start": 5939.96,
"duration": 4.05
},
{
"text": "omit the curly braces I can omit the",
"start": 5942.57,
"duration": 2.01
},
{
"text": "return",
"start": 5944.01,
"duration": 3.36
},
{
"text": "I can just say response arrow response",
"start": 5944.58,
"duration": 4.86
},
{
"text": "Jason and this is a shorthand way of",
"start": 5947.37,
"duration": 4.38
},
{
"text": "saying a function that takes as input",
"start": 5949.44,
"duration": 4.44
},
{
"text": "the response and returns as output",
"start": 5951.75,
"duration": 5.7
},
{
"text": "response to Jason so here I'm saying go",
"start": 5953.88,
"duration": 5.1
},
{
"text": "ahead and fetch me in the latest",
"start": 5957.45,
"duration": 3.71
},
{
"text": "exchange rates from this particular API",
"start": 5958.98,
"duration": 4.83
},
{
"text": "then convert the response to Jason data",
"start": 5961.16,
"duration": 6.88
},
{
"text": "and then once you have the data here's",
"start": 5963.81,
"duration": 6.9
},
{
"text": "what I want you to do with that data and",
"start": 5968.04,
"duration": 4.65
},
{
"text": "for now let's just go ahead and console",
"start": 5970.71,
"duration": 4.38
},
{
"text": "dot log that data just to print it out",
"start": 5972.69,
"duration": 4.08
},
{
"text": "to the terminal so we're not doing",
"start": 5975.09,
"duration": 3.12
},
{
"text": "anything else to us yet all I'm doing is",
"start": 5976.77,
"duration": 3.93
},
{
"text": "saying get me the exchange rates convert",
"start": 5978.21,
"duration": 4.32
},
{
"text": "the exchange rates data into Jason and",
"start": 5980.7,
"duration": 4.41
},
{
"text": "then let's go ahead and print out that",
"start": 5982.53,
"duration": 6.45
},
{
"text": "data so I'll open up currency at HTML",
"start": 5985.11,
"duration": 6.48
},
{
"text": "it's a blank page but if I look in the",
"start": 5988.98,
"duration": 4.8
},
{
"text": "JavaScript inspector I see what got",
"start": 5991.59,
"duration": 4.35
},
{
"text": "logged is a JavaScript object here",
"start": 5993.78,
"duration": 4.2
},
{
"text": "indicated by the word object and if I",
"start": 5995.94,
"duration": 4.35
},
{
"text": "click the triangle at left I can open up",
"start": 5997.98,
"duration": 4.02
},
{
"text": "and see all right inside of this object",
"start": 6000.29,
"duration": 5.75
},
{
"text": "is all of this data about exchange rates",
"start": 6002.0,
"duration": 6.09
},
{
"text": "for a whole bunch of different exchange",
"start": 6006.04,
"duration": 3.61
},
{
"text": "rates for converting from the US dollar",
"start": 6008.09,
"duration": 3.45
},
{
"text": "we're here u.s. dollar one means one",
"start": 6009.65,
"duration": 3.81
},
{
"text": "u.s. dollar is one u.s. dollar for",
"start": 6011.54,
"duration": 5.01
},
{
"text": "example so now that I've got this data",
"start": 6013.46,
"duration": 5.73
},
{
"text": "let's actually try and use this inside",
"start": 6016.55,
"duration": 4.14
},
{
"text": "of the program maybe let's say I want to",
"start": 6019.19,
"duration": 3.87
},
{
"text": "convert between US Dollars and the",
"start": 6020.69,
"duration": 3.54
},
{
"text": "to figure out what the conversion rate",
"start": 6023.06,
"duration": 3.63
},
{
"text": "is between dollars and euros well if we",
"start": 6024.23,
"duration": 4.68
},
{
"text": "recall what the data looks like the data",
"start": 6026.69,
"duration": 5.82
},
{
"text": "is a JavaScript object where we have a",
"start": 6028.91,
"duration": 7.08
},
{
"text": "key called rate and inside of rates is",
"start": 6032.51,
"duration": 5.94
},
{
"text": "this object and inside of that object I",
"start": 6035.99,
"duration": 5.43
},
{
"text": "can access the EU our property to get",
"start": 6038.45,
"duration": 4.77
},
{
"text": "the exchange rate of one US dollar is",
"start": 6041.42,
"duration": 3.72
},
{
"text": "equal to some number of euros for",
"start": 6043.22,
"duration": 4.05
},
{
"text": "example so it's inside of the rates key",
"start": 6045.14,
"duration": 4.83
},
{
"text": "and then inside of the EU our key and",
"start": 6047.27,
"duration": 5.22
},
{
"text": "that's how I know what to get access to",
"start": 6049.97,
"duration": 6.48
},
{
"text": "inside of my data so what I really want",
"start": 6052.49,
"duration": 10.11
},
{
"text": "to do is access data dot rates dot EU R",
"start": 6056.45,
"duration": 8.04
},
{
"text": "it says get me to all the data that came",
"start": 6062.6,
"duration": 4.95
},
{
"text": "back access the rates key and then",
"start": 6064.49,
"duration": 5.67
},
{
"text": "access the euro key and we'll go ahead",
"start": 6067.55,
"duration": 4.92
},
{
"text": "and save that in a variable called rate",
"start": 6070.16,
"duration": 6.69
},
{
"text": "and now I'll just document query",
"start": 6072.47,
"duration": 7.08
},
{
"text": "selector body dot innerhtml",
"start": 6076.85,
"duration": 5.4
},
{
"text": "equals rate just like take that rate put",
"start": 6079.55,
"duration": 5.64
},
{
"text": "it inside of the body so now if i",
"start": 6082.25,
"duration": 6.03
},
{
"text": "refresh currency dot HTML what I see is",
"start": 6085.19,
"duration": 5.7
},
{
"text": "just this value 0.9 zero eight eight",
"start": 6088.28,
"duration": 3.99
},
{
"text": "four three which means that right now",
"start": 6090.89,
"duration": 3.51
},
{
"text": "one u.s. dollar happens to be equal to",
"start": 6092.27,
"duration": 4.32
},
{
"text": "about zero point nine one euros for",
"start": 6094.4,
"duration": 5.16
},
{
"text": "instance so that's useful I could make",
"start": 6096.59,
"duration": 4.68
},
{
"text": "this a little more human-friendly by",
"start": 6099.56,
"duration": 3.6
},
{
"text": "putting this inside of a template string",
"start": 6101.27,
"duration": 5.13
},
{
"text": "I could say one US dollar is equal to",
"start": 6103.16,
"duration": 8.37
},
{
"text": "and then rate euros for example and so",
"start": 6106.4,
"duration": 8.13
},
{
"text": "now if i refresh the page I see one u.s.",
"start": 6111.53,
"duration": 5.64
},
{
"text": "dollar is equal to this many euros and",
"start": 6114.53,
"duration": 4.38
},
{
"text": "even this is a little bit annoying I",
"start": 6117.17,
"duration": 2.91
},
{
"text": "probably don't care about it too this",
"start": 6118.91,
"duration": 3.18
},
{
"text": "many decimal places and some really in",
"start": 6120.08,
"duration": 3.63
},
{
"text": "the mood to be very precise about these",
"start": 6122.09,
"duration": 3.51
},
{
"text": "exchange rates if I only care about it",
"start": 6123.71,
"duration": 4.14
},
{
"text": "to like 3 decimal places for example it",
"start": 6125.6,
"duration": 4.17
},
{
"text": "turns out JavaScript has functions I can",
"start": 6127.85,
"duration": 4.73
},
{
"text": "use on numbers like rate dot two fixed",
"start": 6129.77,
"duration": 5.76
},
{
"text": "passing in three as an argument there to",
"start": 6132.58,
"duration": 4.39
},
{
"text": "mean I'd like to take this exchange rate",
"start": 6135.53,
"duration": 3.6
},
{
"text": "and just round it to three decimal",
"start": 6136.97,
"duration": 4.8
},
{
"text": "places for example so now i refresh the",
"start": 6139.13,
"duration": 5.16
},
{
"text": "page and I see one u.s. dollar is equal",
"start": 6141.77,
"duration": 4.86
},
{
"text": "to zero point nine zero nine euros and",
"start": 6144.29,
"duration": 3.45
},
{
"text": "the interesting thing about what's",
"start": 6146.63,
"duration": 3.0
},
{
"text": "happening here is this is happening as a",
"start": 6147.74,
"duration": 4.29
},
{
"text": "result of an asynchronous request I am",
"start": 6149.63,
"duration": 4.89
},
{
"text": "asking for the latest exchange rates and",
"start": 6152.03,
"duration": 4.619
},
{
"text": "when I get back the exchange rates date",
"start": 6154.52,
"duration": 4.229
},
{
"text": "javascript is plugging that information",
"start": 6156.649,
"duration": 3.99
},
{
"text": "into the body of the page I now",
"start": 6158.749,
"duration": 4.321
},
{
"text": "communicating with an API getting back",
"start": 6160.639,
"duration": 5.01
},
{
"text": "that api's data in JSON form and then",
"start": 6163.07,
"duration": 5.25
},
{
"text": "using that data to update the contents",
"start": 6165.649,
"duration": 6.09
},
{
"text": "of my HTML page of course in practice if",
"start": 6168.32,
"duration": 5.369
},
{
"text": "I really want a currency exchange web",
"start": 6171.739,
"duration": 3.66
},
{
"text": "page I probably don't just want to",
"start": 6173.689,
"duration": 3.3
},
{
"text": "display the exchange rate between US",
"start": 6175.399,
"duration": 3.691
},
{
"text": "dollars and euros I probably want to let",
"start": 6176.989,
"duration": 4.621
},
{
"text": "the user pick what currencies they would",
"start": 6179.09,
"duration": 4.649
},
{
"text": "like to exchange between and so here's",
"start": 6181.61,
"duration": 5.94
},
{
"text": "how I might go about doing that inside",
"start": 6183.739,
"duration": 5.82
},
{
"text": "of the body of the page now rather than",
"start": 6187.55,
"duration": 3.899
},
{
"text": "just have an empty body let's go ahead",
"start": 6189.559,
"duration": 4.02
},
{
"text": "and add a form that form is going to",
"start": 6191.449,
"duration": 4.411
},
{
"text": "have an input whose ID is currency just",
"start": 6193.579,
"duration": 3.63
},
{
"text": "so I have a way of referencing it later",
"start": 6195.86,
"duration": 3.629
},
{
"text": "the place holder will just be currency",
"start": 6197.209,
"duration": 5.64
},
{
"text": "and the type of it is text and then I'll",
"start": 6199.489,
"duration": 5.7
},
{
"text": "have an input whose type is submit and",
"start": 6202.849,
"duration": 4.681
},
{
"text": "we'll give it a value of convert that'll",
"start": 6205.189,
"duration": 3.69
},
{
"text": "be what the button says it says convert",
"start": 6207.53,
"duration": 3.27
},
{
"text": "and then I can convert to a particular",
"start": 6208.879,
"duration": 4.68
},
{
"text": "currency and then I need some place to",
"start": 6210.8,
"duration": 5.129
},
{
"text": "put my results so I'll go ahead and add",
"start": 6213.559,
"duration": 5.82
},
{
"text": "a div whose ID is result and this is",
"start": 6215.929,
"duration": 4.98
},
{
"text": "where after I've done all the currency",
"start": 6219.379,
"duration": 3.211
},
{
"text": "conversion this is where I'm going to",
"start": 6220.909,
"duration": 3.48
},
{
"text": "put the results of doing that currency",
"start": 6222.59,
"duration": 5.67
},
{
"text": "conversion so now rather than fetch",
"start": 6224.389,
"duration": 5.46
},
{
"text": "right away here's what I need to do I",
"start": 6228.26,
"duration": 4.109
},
{
"text": "need to do something only when the form",
"start": 6229.849,
"duration": 3.241
},
{
"text": "is submitted",
"start": 6232.369,
"duration": 3.661
},
{
"text": "so I can get the form by saying document",
"start": 6233.09,
"duration": 6.989
},
{
"text": "query selector form dot on submit equals",
"start": 6236.03,
"duration": 6.359
},
{
"text": "this function and I'm gonna go ahead and",
"start": 6240.079,
"duration": 4.62
},
{
"text": "just in advance return false at the end",
"start": 6242.389,
"duration": 4.23
},
{
"text": "of the function so we don't actually try",
"start": 6244.699,
"duration": 3.54
},
{
"text": "and submit the form to another page I",
"start": 6246.619,
"duration": 3.33
},
{
"text": "just want to run everything locally on",
"start": 6248.239,
"duration": 5.101
},
{
"text": "this same page but now inside of this",
"start": 6249.949,
"duration": 6.42
},
{
"text": "form once you submit it that is when I",
"start": 6253.34,
"duration": 5.159
},
{
"text": "want to run this code that is going to",
"start": 6256.369,
"duration": 4.56
},
{
"text": "fetch new data so I'm going to fetch",
"start": 6258.499,
"duration": 5.16
},
{
"text": "data from the exchange rates API convert",
"start": 6260.929,
"duration": 5.04
},
{
"text": "that data to Jason same as before then",
"start": 6263.659,
"duration": 4.621
},
{
"text": "go ahead and get access to that data but",
"start": 6265.969,
"duration": 4.351
},
{
"text": "now what I want to do is I want to",
"start": 6268.28,
"duration": 4.919
},
{
"text": "figure out what the user actually typed",
"start": 6270.32,
"duration": 4.98
},
{
"text": "in to the input field and that is going",
"start": 6273.199,
"duration": 3.3
},
{
"text": "to be the currency that I care about",
"start": 6275.3,
"duration": 2.909
},
{
"text": "getting access to so I'll create a",
"start": 6276.499,
"duration": 3.93
},
{
"text": "variable called currency which will be",
"start": 6278.209,
"duration": 5.46
},
{
"text": "equal to document query selector and I",
"start": 6280.429,
"duration": 4.77
},
{
"text": "write the input field if I scroll down",
"start": 6283.669,
"duration": 4.62
},
{
"text": "it has an ID of currency so if I want to",
"start": 6285.199,
"duration": 4.811
},
{
"text": "get that input field I'm",
"start": 6288.289,
"duration": 4.541
},
{
"text": "to say get the element whose ID is",
"start": 6290.01,
"duration": 7.08
},
{
"text": "currency and get its value so this now",
"start": 6292.83,
"duration": 7.35
},
{
"text": "is the currency that the user wanted me",
"start": 6297.09,
"duration": 7.05
},
{
"text": "to get access to and I can then say data",
"start": 6300.18,
"duration": 9.15
},
{
"text": "rates currency instead of data rates dot",
"start": 6304.14,
"duration": 7.11
},
{
"text": "you are and importantly I can't do data",
"start": 6309.33,
"duration": 4.29
},
{
"text": "rates dot currency that would literally",
"start": 6311.25,
"duration": 4.11
},
{
"text": "try to access a property of rates that",
"start": 6313.62,
"duration": 4.11
},
{
"text": "is called currency if I use square",
"start": 6315.36,
"duration": 4.5
},
{
"text": "brackets instead that allows me to use a",
"start": 6317.73,
"duration": 3.96
},
{
"text": "variable something like the currency",
"start": 6319.86,
"duration": 3.54
},
{
"text": "variable which are defined up here on",
"start": 6321.69,
"duration": 4.29
},
{
"text": "line 13 as the currency that the user",
"start": 6323.4,
"duration": 4.59
},
{
"text": "typed in I would like to access that",
"start": 6325.98,
"duration": 4.7
},
{
"text": "particular currency inside of the rates",
"start": 6327.99,
"duration": 6.03
},
{
"text": "and so now I can ask a question there",
"start": 6330.68,
"duration": 5.11
},
{
"text": "are two possibilities here either the",
"start": 6334.02,
"duration": 4.11
},
{
"text": "currency the user typed in it is a valid",
"start": 6335.79,
"duration": 5.28
},
{
"text": "currency or it's not and it turns out",
"start": 6338.13,
"duration": 5.13
},
{
"text": "that if you try and access a property of",
"start": 6341.07,
"duration": 4.32
},
{
"text": "an object that doesn't exist what you",
"start": 6343.26,
"duration": 3.42
},
{
"text": "get back is a particular JavaScript",
"start": 6345.39,
"duration": 3.66
},
{
"text": "variable called undefined meaning there",
"start": 6346.68,
"duration": 5.04
},
{
"text": "is no value there so for example if I",
"start": 6349.05,
"duration": 5.61
},
{
"text": "have something like let person equal",
"start": 6351.72,
"duration": 5.82
},
{
"text": "first name is Harry and last name is",
"start": 6354.66,
"duration": 5.61
},
{
"text": "Potter like we did before I can access",
"start": 6357.54,
"duration": 5.04
},
{
"text": "something like person dot first and get",
"start": 6360.27,
"duration": 4.71
},
{
"text": "Harry I can access person dot last and",
"start": 6362.58,
"duration": 4.47
},
{
"text": "get Potter but if I access person dot",
"start": 6364.98,
"duration": 4.08
},
{
"text": "middle that is going to be a special",
"start": 6367.05,
"duration": 3.99
},
{
"text": "variable in JavaScript or a special",
"start": 6369.06,
"duration": 3.99
},
{
"text": "value in JavaScript called undefined",
"start": 6371.04,
"duration": 5.31
},
{
"text": "meaning there is no value there it's",
"start": 6373.05,
"duration": 4.77
},
{
"text": "slightly different from null which also",
"start": 6376.35,
"duration": 3.12
},
{
"text": "has a similar meaning they're used in",
"start": 6377.82,
"duration": 3.78
},
{
"text": "slightly different contexts so here what",
"start": 6379.47,
"duration": 5.06
},
{
"text": "I can say is if the rate is not",
"start": 6381.6,
"duration": 7.05
},
{
"text": "undefined well then let's go ahead and",
"start": 6384.53,
"duration": 10.96
},
{
"text": "update not the body but the result to",
"start": 6388.65,
"duration": 10.05
},
{
"text": "say one u.s. dollar is equal to this",
"start": 6395.49,
"duration": 6.96
},
{
"text": "rate not necessarily euros but whatever",
"start": 6398.7,
"duration": 7.85
},
{
"text": "the currency happens to be and otherwise",
"start": 6402.45,
"duration": 6.51
},
{
"text": "let's go ahead and document query",
"start": 6406.55,
"duration": 6.81
},
{
"text": "selector result dot inner HTML equals",
"start": 6408.96,
"duration": 7.44
},
{
"text": "invalid currency just to let the user",
"start": 6413.36,
"duration": 4.6
},
{
"text": "know that the currency they tried to",
"start": 6416.4,
"duration": 3.87
},
{
"text": "provide is not actually a valid currency",
"start": 6417.96,
"duration": 4.08
},
{
"text": "and so we're going to need to try a",
"start": 6420.27,
"duration": 3.28
},
{
"text": "different currency in order to get the",
"start": 6422.04,
"duration": 4.3
},
{
"text": "all to work so now here's what we can do",
"start": 6423.55,
"duration": 5.58
},
{
"text": "if I open up currency dot HTML again I",
"start": 6426.34,
"duration": 5.219
},
{
"text": "now see a form where I can type in a",
"start": 6429.13,
"duration": 4.259
},
{
"text": "currency I can type in something like",
"start": 6431.559,
"duration": 4.35
},
{
"text": "the Europe for example press convert and",
"start": 6433.389,
"duration": 4.381
},
{
"text": "I see alright one u.s. dollar equal to",
"start": 6435.909,
"duration": 5.58
},
{
"text": "0.9 0.0 something like the pound press",
"start": 6437.77,
"duration": 6.03
},
{
"text": "convert one u.s. dollar equal to 0.77",
"start": 6441.489,
"duration": 4.98
},
{
"text": "one pounds I type in the Japanese yen",
"start": 6443.8,
"duration": 4.859
},
{
"text": "one u.s. dollar is equal to 109 point",
"start": 6446.469,
"duration": 4.351
},
{
"text": "eight five two Japanese yen and all of",
"start": 6448.659,
"duration": 3.54
},
{
"text": "this is happening where every time I",
"start": 6450.82,
"duration": 3.21
},
{
"text": "submit the form it's making yet another",
"start": 6452.199,
"duration": 4.261
},
{
"text": "request so if the exchange rates happen",
"start": 6454.03,
"duration": 3.99
},
{
"text": "to change in between when I submit the",
"start": 6456.46,
"duration": 3.599
},
{
"text": "form the next time I submit the form I",
"start": 6458.02,
"duration": 3.51
},
{
"text": "will be getting the latest exchange",
"start": 6460.059,
"duration": 3.361
},
{
"text": "rates according to that exchange rates",
"start": 6461.53,
"duration": 4.08
},
{
"text": "API and the results are going to come",
"start": 6463.42,
"duration": 3.989
},
{
"text": "back here and of course if I type in a",
"start": 6465.61,
"duration": 3.719
},
{
"text": "currency that doesn't exist I type in",
"start": 6467.409,
"duration": 3.81
},
{
"text": "something like foo for example and press",
"start": 6469.329,
"duration": 4.261
},
{
"text": "convert invalid currency so it's going",
"start": 6471.219,
"duration": 4.051
},
{
"text": "to report back to me that it wasn't able",
"start": 6473.59,
"duration": 3.569
},
{
"text": "to find that currency and so it tells me",
"start": 6475.27,
"duration": 3.21
},
{
"text": "that I need to type in something valid",
"start": 6477.159,
"duration": 2.94
},
{
"text": "and so I can type in something valid",
"start": 6478.48,
"duration": 3.84
},
{
"text": "maybe I try just US dollars itself it",
"start": 6480.099,
"duration": 5.011
},
{
"text": "tells me one u.s. dollar is equal to one",
"start": 6482.32,
"duration": 4.68
},
{
"text": "US dollar exactly what I would expect it",
"start": 6485.11,
"duration": 4.469
},
{
"text": "to be now there are a couple of",
"start": 6487.0,
"duration": 4.11
},
{
"text": "optimizations and improvements that we",
"start": 6489.579,
"duration": 3.421
},
{
"text": "can make here one is that I can search",
"start": 6491.11,
"duration": 3.81
},
{
"text": "for euros right now with EU our press",
"start": 6493.0,
"duration": 4.05
},
{
"text": "convert but if I search for euros in",
"start": 6494.92,
"duration": 4.71
},
{
"text": "lower case for example it turns out it",
"start": 6497.05,
"duration": 4.2
},
{
"text": "thinks that's an invalid currency and",
"start": 6499.63,
"duration": 4.77
},
{
"text": "the reason why is because if you look at",
"start": 6501.25,
"duration": 4.8
},
{
"text": "the data that comes back to me from the",
"start": 6504.4,
"duration": 3.36
},
{
"text": "API this is the data that I get back",
"start": 6506.05,
"duration": 4.109
},
{
"text": "from the exchange rates API what you'll",
"start": 6507.76,
"duration": 4.319
},
{
"text": "notice is that all of the currencies are",
"start": 6510.159,
"duration": 3.841
},
{
"text": "all in capital letters that are all",
"start": 6512.079,
"duration": 3.451
},
{
"text": "capital letters all capital letters",
"start": 6514.0,
"duration": 3.599
},
{
"text": "which means the only keys that I'm",
"start": 6515.53,
"duration": 4.379
},
{
"text": "allowed to access are in fact those that",
"start": 6517.599,
"duration": 3.691
},
{
"text": "have capital letters in them because",
"start": 6519.909,
"duration": 3.21
},
{
"text": "these are the only keys that this API",
"start": 6521.29,
"duration": 4.53
},
{
"text": "makes available to me so if I want to",
"start": 6523.119,
"duration": 4.921
},
{
"text": "convert between US dollars and euros",
"start": 6525.82,
"duration": 4.589
},
{
"text": "lowercase what I might want to do is",
"start": 6528.04,
"duration": 4.92
},
{
"text": "first take the currency the thing the",
"start": 6530.409,
"duration": 6.54
},
{
"text": "user typed in and first just call to",
"start": 6532.96,
"duration": 6.0
},
{
"text": "uppercase on it which is a JavaScript",
"start": 6536.949,
"duration": 3.42
},
{
"text": "function that takes a string and",
"start": 6538.96,
"duration": 3.449
},
{
"text": "converts it Dabra case I'd like to take",
"start": 6540.369,
"duration": 3.931
},
{
"text": "whatever the user typed in and now just",
"start": 6542.409,
"duration": 3.931
},
{
"text": "first convert it to uppercase that way",
"start": 6544.3,
"duration": 4.77
},
{
"text": "if I go back here I can type in Euro",
"start": 6546.34,
"duration": 5.219
},
{
"text": "lowercase press convert and I'm still",
"start": 6549.07,
"duration": 4.94
},
{
"text": "able to get the correct conversion rate",
"start": 6551.559,
"duration": 4.861
},
{
"text": "the other thing that we won't noticeably",
"start": 6554.01,
"duration": 3.34
},
{
"text": "notice the difference with",
"start": 6556.42,
"duration": 3.6
},
{
"text": "is that right now I'm assuming that all",
"start": 6557.35,
"duration": 4.56
},
{
"text": "of this is going to go successfully that",
"start": 6560.02,
"duration": 3.3
},
{
"text": "we're gonna successfully be able to make",
"start": 6561.91,
"duration": 3.3
},
{
"text": "a web request will successfully convert",
"start": 6563.32,
"duration": 3.72
},
{
"text": "the response back to Jason but you never",
"start": 6565.21,
"duration": 3.93
},
{
"text": "know an API could go down the API could",
"start": 6567.04,
"duration": 3.84
},
{
"text": "change and do something unexpected and",
"start": 6569.14,
"duration": 3.42
},
{
"text": "so anytime you're dealing with these",
"start": 6570.88,
"duration": 3.15
},
{
"text": "types of promises where you fetch",
"start": 6572.56,
"duration": 3.45
},
{
"text": "something and say then do this then do",
"start": 6574.03,
"duration": 4.53
},
{
"text": "that it can often be a good idea to add",
"start": 6576.01,
"duration": 6.24
},
{
"text": "one last case which is a catch case that",
"start": 6578.56,
"duration": 5.34
},
{
"text": "basically says what should you do if",
"start": 6582.25,
"duration": 4.11
},
{
"text": "something goes wrong so I can say catch",
"start": 6583.9,
"duration": 4.2
},
{
"text": "the error and what I can just do is say",
"start": 6586.36,
"duration": 6.3
},
{
"text": "like console dot log error and then log",
"start": 6588.1,
"duration": 6.18
},
{
"text": "the error there and all that's really",
"start": 6592.66,
"duration": 3.87
},
{
"text": "saying is that if anything above goes",
"start": 6594.28,
"duration": 3.96
},
{
"text": "wrong with the fetching and trying to",
"start": 6596.53,
"duration": 3.72
},
{
"text": "process the response it's gonna catch",
"start": 6598.24,
"duration": 4.17
},
{
"text": "the error and then we'll just like print",
"start": 6600.25,
"duration": 3.96
},
{
"text": "out to the console that something went",
"start": 6602.41,
"duration": 3.72
},
{
"text": "wrong some error message happened and so",
"start": 6604.21,
"duration": 3.72
},
{
"text": "that can be a helpful nice to have just",
"start": 6606.13,
"duration": 3.39
},
{
"text": "to make sure that when things crash they",
"start": 6607.93,
"duration": 3.09
},
{
"text": "crash in a predictable way that you're",
"start": 6609.52,
"duration": 3.45
},
{
"text": "able to see exactly what the error is",
"start": 6611.02,
"duration": 4.44
},
{
"text": "and just by looking inside the",
"start": 6612.97,
"duration": 4.68
},
{
"text": "JavaScript console and so now we have a",
"start": 6615.46,
"duration": 4.5
},
{
"text": "fully working web page that is able to",
"start": 6617.65,
"duration": 4.71
},
{
"text": "communicate with an external API that is",
"start": 6619.96,
"duration": 4.53
},
{
"text": "able to ask for information from another",
"start": 6622.36,
"duration": 3.27
},
{
"text": "service on the Internet",
"start": 6624.49,
"duration": 3.27
},
{
"text": "use those results and put them back into",
"start": 6625.63,
"duration": 4.29
},
{
"text": "the page really just going to show the",
"start": 6627.76,
"duration": 4.02
},
{
"text": "power now that we get by taking",
"start": 6629.92,
"duration": 4.32
},
{
"text": "advantage of the JavaScript language we",
"start": 6631.78,
"duration": 4.65
},
{
"text": "have the ability now to not only use",
"start": 6634.24,
"duration": 4.08
},
{
"text": "JavaScript to be able to run code on the",
"start": 6636.43,
"duration": 3.54
},
{
"text": "client where we weren't able to before",
"start": 6638.32,
"duration": 3.72
},
{
"text": "were right before we only had Python",
"start": 6639.97,
"duration": 3.78
},
{
"text": "code that was running on a web server",
"start": 6642.04,
"duration": 4.2
},
{
"text": "but using JavaScript the really powerful",
"start": 6643.75,
"duration": 4.44
},
{
"text": "thing is now the ability to manipulate",
"start": 6646.24,
"duration": 4.05
},
{
"text": "the dog the ability to use JavaScript to",
"start": 6648.19,
"duration": 4.59
},
{
"text": "take the page and change the contents of",
"start": 6650.29,
"duration": 4.62
},
{
"text": "the page by updating things by reading",
"start": 6652.78,
"duration": 3.54
},
{
"text": "what happens to be on the page whether",
"start": 6654.91,
"duration": 3.12
},
{
"text": "it's inside of a particular element or",
"start": 6656.32,
"duration": 3.3
},
{
"text": "what a user happened to type in and",
"start": 6658.03,
"duration": 4.2
},
{
"text": "using that in conjunction with event",
"start": 6659.62,
"duration": 4.68
},
{
"text": "handlers ways that we can listen for",
"start": 6662.23,
"duration": 3.57
},
{
"text": "when the user clicks on something or",
"start": 6664.3,
"duration": 2.97
},
{
"text": "when the user Scrolls through something",
"start": 6665.8,
"duration": 3.54
},
{
"text": "or when the user types a key to be able",
"start": 6667.27,
"duration": 3.66
},
{
"text": "to respond and therefore make our",
"start": 6669.34,
"duration": 4.62
},
{
"text": "webpages all the more interactive next",
"start": 6670.93,
"duration": 4.59
},
{
"text": "time we'll continue our discussion of",
"start": 6673.96,
"duration": 2.94
},
{
"text": "JavaScript looking at how we can",
"start": 6675.52,
"duration": 3.24
},
{
"text": "leverage the features of JavaScript to",
"start": 6676.9,
"duration": 3.57
},
{
"text": "continue to build even more interesting",
"start": 6678.76,
"duration": 3.57
},
{
"text": "and engaging user interfaces so we'll",
"start": 6680.47,
"duration": 4.46
},
{
"text": "see you next time",
"start": 6682.33,
"duration": 2.6
}
]