File size: 6,234 Bytes
9d1374f
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
/* eslint no-console:0 */

import katex from "katex";
import splitAtDelimiters from "./splitAtDelimiters";
import type {DelimiterSpec} from "./splitAtDelimiters";

interface RenderMathInElementOptions {
    delimiters?: DelimiterSpec[];
    preProcess?: (math: string) => string;
    ignoredTags?: string[];
    ignoredClasses?: string[];
    errorCallback?: (msg: string, err: Error) => void;
    displayMode?: boolean;
    macros?: Record<string, string>;
}

interface RenderMathInElementOptionsCopy {
    delimiters: DelimiterSpec[];
    preProcess?: (math: string) => string;
    ignoredTags: Set<string>;
    ignoredClasses: string[];
    errorCallback: (msg: string, err: Error) => void;
    displayMode?: boolean;
    macros?: Record<string, string>;
}

/* Note: optionsCopy is mutated by this method. If it is ever exposed in the
 * API, we should copy it before mutating.
 */
const renderMathInText = function(
    text: string,
    optionsCopy: RenderMathInElementOptionsCopy
) {
    const data = splitAtDelimiters(text, optionsCopy.delimiters);
    if (data.length === 1 && data[0].type === 'text') {
        // There is no formula in the text.
        // Let's return null which means there is no need to replace
        // the current text node with a new one.
        return null;
    }

    const fragment = document.createDocumentFragment();

    for (let i = 0; i < data.length; i++) {
        if (data[i].type === "text") {
            fragment.appendChild(document.createTextNode(data[i].data));
        } else {
            const span = document.createElement("span");
            let math = data[i].data;
            // Override any display mode defined in the settings with that
            // defined by the text itself
            optionsCopy.displayMode = data[i].display;
            try {
                if (optionsCopy.preProcess) {
                    math = optionsCopy.preProcess(math);
                }
                katex.render(math, span, optionsCopy);
            } catch (e) {
                if (!(e instanceof katex.ParseError)) {
                    throw e;
                }
                optionsCopy.errorCallback(
                    "KaTeX auto-render: Failed to parse `" + data[i].data +
                        "` with ",
                    e
                );
                fragment.appendChild(document.createTextNode(data[i].rawData!));
                continue;
            }
            fragment.appendChild(span);
        }
    }

    return fragment;
};

const renderElem = function(
    elem: HTMLElement,
    optionsCopy: RenderMathInElementOptionsCopy
) {
    for (let i = 0; i < elem.childNodes.length; i++) {
        const childNode = elem.childNodes[i];
        if (childNode.nodeType === 3) {
            // Text node
            // Concatenate all sibling text nodes.
            // Webkit browsers split very large text nodes into smaller ones,
            // so the delimiters may be split across different nodes.
            let textContentConcat = childNode.textContent ?? "";
            let sibling = childNode.nextSibling;
            let nSiblings = 0;
            while (sibling && (sibling.nodeType === Node.TEXT_NODE)) {
                textContentConcat += sibling.textContent ?? "";
                sibling = sibling.nextSibling;
                nSiblings++;
            }
            const frag = renderMathInText(textContentConcat, optionsCopy);
            if (frag) {
                // Remove extra text nodes
                for (let j = 0; j < nSiblings; j++) {
                    childNode.nextSibling!.remove();
                }
                i += frag.childNodes.length - 1;
                elem.replaceChild(frag, childNode);
            } else {
                // If the concatenated text does not contain math
                // the siblings will not either
                i += nSiblings;
            }
        } else if (childNode.nodeType === 1) {
            // Element node
            const className = ' ' + (childNode as HTMLElement).className + ' ';
            const shouldRender = !optionsCopy.ignoredTags.has(
                childNode.nodeName.toLowerCase()) &&
                  optionsCopy.ignoredClasses.every(
                      (x: string) => !className.includes(' ' + x + ' '));

            if (shouldRender) {
                renderElem(childNode as HTMLElement, optionsCopy);
            }
        }
        // Otherwise, it's something else, and ignore it.
    }
};

const renderMathInElement = function(elem: HTMLElement, options?: RenderMathInElementOptions) {
    if (!elem) {
        throw new Error("No element provided to render");
    }

    const optionsCopy: Partial<RenderMathInElementOptionsCopy> = {};

    Object.assign(optionsCopy, options);

    // default options
    optionsCopy.delimiters = optionsCopy.delimiters || [
        {left: "$$", right: "$$", display: true},
        {left: "\\(", right: "\\)", display: false},
        // LaTeX uses $…$, but it ruins the display of normal `$` in text:
        // {left: "$", right: "$", display: false},
        // $ must come after $$

        // Render AMS environments even if outside $$…$$ delimiters.
        {left: "\\begin{equation}", right: "\\end{equation}", display: true},
        {left: "\\begin{align}", right: "\\end{align}", display: true},
        {left: "\\begin{alignat}", right: "\\end{alignat}", display: true},
        {left: "\\begin{gather}", right: "\\end{gather}", display: true},
        {left: "\\begin{CD}", right: "\\end{CD}", display: true},

        {left: "\\[", right: "\\]", display: true},
    ];
    optionsCopy.ignoredTags = new Set<string>(options?.ignoredTags || [
        "script", "noscript", "style", "textarea", "pre", "code", "option",
    ]);
    optionsCopy.ignoredClasses = optionsCopy.ignoredClasses || [];
    optionsCopy.errorCallback = optionsCopy.errorCallback || console.error;

    // Enable sharing of global macros defined via `\gdef` between different
    // math elements within a single call to `renderMathInElement`.
    optionsCopy.macros = optionsCopy.macros || {};

    renderElem(elem, optionsCopy as RenderMathInElementOptionsCopy);
};

export default renderMathInElement;