1/**
 2 * A plugin which enables rendering of math equations inside
 3 * of reveal.js slides. Essentially a thin wrapper for MathJax 3
 4 *
 5 * @author Hakim El Hattab
 6 * @author Gerhard Burger
 7 */
 8export const MathJax3 = () => {
 9
10    // The reveal.js instance this plugin is attached to
11    let deck;
12
13    let defaultOptions = {
14        tex: {
15            inlineMath: [ [ '$', '$' ], [ '\\(', '\\)' ]  ]
16        },
17        options: {
18            skipHtmlTags: [ 'script', 'noscript', 'style', 'textarea', 'pre' ]
19        },
20        startup: {
21            ready: () => {
22                MathJax.startup.defaultReady();
23                MathJax.startup.promise.then(() => {
24                    Reveal.layout();
25                });
26            }
27        }
28    };
29
30    function loadScript( url, callback ) {
31
32        let script = document.createElement( 'script' );
33        script.type = "text/javascript"
34        script.id = "MathJax-script"
35        script.src = url;
36        script.async = true
37
38        // Wrapper for callback to make sure it only fires once
39        script.onload = () => {
40            if (typeof callback === 'function') {
41                callback.call();
42                callback = null;
43            }
44        };
45
46        document.head.appendChild( script );
47
48    }
49
50    return {
51        id: 'mathjax3',
52        init: function(reveal) {
53
54            deck = reveal;
55
56            let revealOptions = deck.getConfig().mathjax3 || {};
57            let options = {...defaultOptions, ...revealOptions};
58            options.tex = {...defaultOptions.tex, ...revealOptions.tex}
59            options.options = {...defaultOptions.options, ...revealOptions.options}
60            options.startup = {...defaultOptions.startup, ...revealOptions.startup}
61
62            let url = options.mathjax || 'https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js';
63            options.mathjax = null;
64
65            window.MathJax = options;
66
67            loadScript( url, function() {
68                // Reprocess equations in slides when they turn visible
69                Reveal.addEventListener( 'slidechanged', function( event ) {
70                    MathJax.typeset();
71                } );
72            } );
73
74        }
75    }
76
77};