Christophe Dervieux | 8afae13 | 2021-12-06 15:16:42 +0100 | [diff] [blame] | 1 | /** |
| 2 | * A plugin which enables rendering of math equations inside |
| 3 | * of reveal.js slides. Essentially a thin wrapper for KaTeX. |
| 4 | * |
| 5 | * @author Hakim El Hattab |
| 6 | * @author Gerhard Burger |
| 7 | */ |
| 8 | export const KaTeX = () => { |
| 9 | let deck; |
| 10 | |
| 11 | let defaultOptions = { |
| 12 | version: 'latest', |
| 13 | delimiters: [ |
| 14 | {left: '$$', right: '$$', display: true}, // Note: $$ has to come before $ |
| 15 | {left: '$', right: '$', display: false}, |
| 16 | {left: '\\(', right: '\\)', display: false}, |
| 17 | {left: '\\[', right: '\\]', display: true} |
| 18 | ], |
| 19 | ignoredTags: ['script', 'noscript', 'style', 'textarea', 'pre'] |
| 20 | } |
| 21 | |
| 22 | const loadCss = src => { |
| 23 | let link = document.createElement('link'); |
| 24 | link.rel = 'stylesheet'; |
| 25 | link.href = src; |
| 26 | document.head.appendChild(link); |
| 27 | }; |
| 28 | |
| 29 | /** |
| 30 | * Loads a JavaScript file and returns a Promise for when it is loaded |
| 31 | * Credits: https://aaronsmith.online/easily-load-an-external-script-using-javascript/ |
| 32 | */ |
| 33 | const loadScript = src => { |
| 34 | return new Promise((resolve, reject) => { |
| 35 | const script = document.createElement('script') |
| 36 | script.type = 'text/javascript' |
| 37 | script.onload = resolve |
| 38 | script.onerror = reject |
| 39 | script.src = src |
| 40 | document.head.append(script) |
| 41 | }) |
| 42 | }; |
| 43 | |
| 44 | async function loadScripts(urls) { |
| 45 | for(const url of urls) { |
| 46 | await loadScript(url); |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | return { |
| 51 | id: 'katex', |
| 52 | |
| 53 | init: function (reveal) { |
| 54 | |
| 55 | deck = reveal; |
| 56 | |
| 57 | let revealOptions = deck.getConfig().katex || {}; |
| 58 | |
| 59 | let options = {...defaultOptions, ...revealOptions}; |
| 60 | const {local, version, extensions, ...katexOptions} = options; |
| 61 | |
| 62 | let baseUrl = options.local || 'https://cdn.jsdelivr.net/npm/katex'; |
| 63 | let versionString = options.local ? '' : '@' + options.version; |
| 64 | |
| 65 | let cssUrl = baseUrl + versionString + '/dist/katex.min.css'; |
| 66 | let katexUrl = baseUrl + versionString + '/dist/katex.min.js'; |
| 67 | let mhchemUrl = baseUrl + versionString + '/dist/contrib/mhchem.min.js' |
| 68 | let karUrl = baseUrl + versionString + '/dist/contrib/auto-render.min.js'; |
| 69 | |
| 70 | let katexScripts = [katexUrl]; |
| 71 | if(options.extensions && options.extensions.includes("mhchem")) { |
| 72 | katexScripts.push(mhchemUrl); |
| 73 | } |
| 74 | katexScripts.push(karUrl); |
| 75 | |
| 76 | const renderMath = () => { |
| 77 | renderMathInElement(reveal.getSlidesElement(), katexOptions); |
| 78 | deck.layout(); |
| 79 | } |
| 80 | |
| 81 | loadCss(cssUrl); |
| 82 | |
| 83 | // For some reason dynamically loading with defer attribute doesn't result in the expected behavior, the below code does |
| 84 | loadScripts(katexScripts).then(() => { |
| 85 | if( deck.isReady() ) { |
| 86 | renderMath(); |
| 87 | } |
| 88 | else { |
| 89 | deck.on( 'ready', renderMath.bind( this ) ); |
| 90 | } |
| 91 | }); |
| 92 | |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | }; |