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why-cant-we-deploy-today/plugin/math/math.js

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JavaScript
Executable File

/**
* A plugin which enables rendering of math equations inside
* of reveal.js slides. Essentially a thin wrapper for MathJax.
*
* @author Hakim El Hattab
*/
const Plugin = () => {
// The reveal.js instance this plugin is attached to
let deck;
let defaultOptions = {
messageStyle: 'none',
tex2jax: {
inlineMath: [ [ '$', '$' ], [ '\\(', '\\)' ] ],
skipTags: [ 'script', 'noscript', 'style', 'textarea', 'pre' ]
},
skipStartupTypeset: true
};
function loadScript( url, callback ) {
let head = document.querySelector( 'head' );
let script = document.createElement( 'script' );
script.type = 'text/javascript';
script.src = url;
// Wrapper for callback to make sure it only fires once
let finish = () => {
if( typeof callback === 'function' ) {
callback.call();
callback = null;
}
}
script.onload = finish;
// IE
script.onreadystatechange = () => {
if ( this.readyState === 'loaded' ) {
finish();
}
}
// Normal browsers
head.appendChild( script );
}
return {
id: 'math',
init: function( reveal ) {
deck = reveal;
let revealOptions = deck.getConfig().math || {};
let options = { ...defaultOptions, ...revealOptions };
let mathjax = options.mathjax || 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js';
let config = options.config || 'TeX-AMS_HTML-full';
let url = mathjax + '?config=' + config;
options.tex2jax = { ...defaultOptions.tex2jax, ...revealOptions.tex2jax };
options.mathjax = options.config = null;
loadScript( url, function() {
MathJax.Hub.Config( options );
// Typeset followed by an immediate reveal.js layout since
// the typesetting process could affect slide height
MathJax.Hub.Queue( [ 'Typeset', MathJax.Hub, deck.getRevealElement() ] );
MathJax.Hub.Queue( deck.layout );
// Reprocess equations in slides when they turn visible
deck.on( 'slidechanged', function( event ) {
MathJax.Hub.Queue( [ 'Typeset', MathJax.Hub, event.currentSlide ] );
} );
} );
}
}
};
export default Plugin;