1/**
 2 * A plugin which enables rendering of math equations inside
 3 * of reveal.js slides. Essentially a thin wrapper for MathJax.
 4 *
 5 * @author Hakim El Hattab
 6 */
 7export const MathJax2 = () => {
 8
 9	// The reveal.js instance this plugin is attached to
10	let deck;
11
12	let defaultOptions = {
13		messageStyle: 'none',
14		tex2jax: {
15			inlineMath: [ [ '$', '$' ], [ '\\(', '\\)' ] ],
16			skipTags: [ 'script', 'noscript', 'style', 'textarea', 'pre' ]
17		},
18		skipStartupTypeset: true
19	};
20
21	function loadScript( url, callback ) {
22
23		let head = document.querySelector( 'head' );
24		let script = document.createElement( 'script' );
25		script.type = 'text/javascript';
26		script.src = url;
27
28		// Wrapper for callback to make sure it only fires once
29		let finish = () => {
30			if( typeof callback === 'function' ) {
31				callback.call();
32				callback = null;
33			}
34		}
35
36		script.onload = finish;
37
38		// IE
39		script.onreadystatechange = () => {
40			if ( this.readyState === 'loaded' ) {
41				finish();
42			}
43		}
44
45		// Normal browsers
46		head.appendChild( script );
47
48	}
49
50	return {
51		id: 'mathjax2',
52
53		init: function( reveal ) {
54
55			deck = reveal;
56
57			let revealOptions = deck.getConfig().mathjax2 || deck.getConfig().math || {};
58
59			let options = { ...defaultOptions, ...revealOptions };
60			let mathjax = options.mathjax || 'https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js';
61			let config = options.config || 'TeX-AMS_HTML-full';
62			let url = mathjax + '?config=' + config;
63
64			options.tex2jax = { ...defaultOptions.tex2jax, ...revealOptions.tex2jax };
65
66			options.mathjax = options.config = null;
67
68			loadScript( url, function() {
69
70				MathJax.Hub.Config( options );
71
72				// Typeset followed by an immediate reveal.js layout since
73				// the typesetting process could affect slide height
74				MathJax.Hub.Queue( [ 'Typeset', MathJax.Hub, deck.getRevealElement() ] );
75				MathJax.Hub.Queue( deck.layout );
76
77				// Reprocess equations in slides when they turn visible
78				deck.on( 'slidechanged', function( event ) {
79
80					MathJax.Hub.Queue( [ 'Typeset', MathJax.Hub, event.currentSlide ] );
81
82				} );
83
84			} );
85
86		}
87	}
88
89};