1 files changed, 96 insertions, 0 deletions
diff --git a/geschichte/plugin/math/katex.js b/geschichte/plugin/math/katex.js
new file mode 100755
index 0000000..a8b47c4
--- /dev/null
+++ b/geschichte/plugin/math/katex.js
@@ -0,0 +1,96 @@
+/**
+ * A plugin which enables rendering of math equations inside
+ * of reveal.js slides. Essentially a thin wrapper for KaTeX.
+ *
+ * @author Hakim El Hattab
+ * @author Gerhard Burger
+ */
+export const KaTeX = () => {
+	let deck;
+
+	let defaultOptions = {
+		version: 'latest',
+		delimiters: [
+			{left: '$$', right: '$$', display: true}, // Note: $$ has to come before $
+			{left: '$', right: '$', display: false},
+			{left: '\\(', right: '\\)', display: false},
+			{left: '\\[', right: '\\]', display: true}
+		],
+		ignoredTags: ['script', 'noscript', 'style', 'textarea', 'pre']
+	}
+
+	const loadCss = src => {
+		let link = document.createElement('link');
+		link.rel = 'stylesheet';
+		link.href = src;
+		document.head.appendChild(link);
+	};
+
+	/**
+	 * Loads a JavaScript file and returns a Promise for when it is loaded
+	 * Credits: https://aaronsmith.online/easily-load-an-external-script-using-javascript/
+	 */
+	const loadScript = src => {
+		return new Promise((resolve, reject) => {
+			const script = document.createElement('script')
+			script.type = 'text/javascript'
+			script.onload = resolve
+			script.onerror = reject
+			script.src = src
+			document.head.append(script)
+		})
+	};
+
+	async function loadScripts(urls) {
+		for(const url of urls) {
+			await loadScript(url);
+		}
+	}
+
+	return {
+		id: 'katex',
+
+		init: function (reveal) {
+
+			deck = reveal;
+
+			let revealOptions = deck.getConfig().katex || {};
+
+			let options = {...defaultOptions, ...revealOptions};
+			const {local, version, extensions, ...katexOptions} = options;
+
+			let baseUrl = options.local || 'https://cdn.jsdelivr.net/npm/katex';
+			let versionString = options.local ? '' : '@' + options.version;
+
+			let cssUrl = baseUrl + versionString + '/dist/katex.min.css';
+			let katexUrl = baseUrl + versionString + '/dist/katex.min.js';
+			let mhchemUrl = baseUrl + versionString + '/dist/contrib/mhchem.min.js'
+			let karUrl = baseUrl + versionString + '/dist/contrib/auto-render.min.js';
+
+			let katexScripts = [katexUrl];
+			if(options.extensions && options.extensions.includes("mhchem")) {
+				katexScripts.push(mhchemUrl);
+			}
+			katexScripts.push(karUrl);
+
+			const renderMath = () => {
+				renderMathInElement(reveal.getSlidesElement(), katexOptions);
+				deck.layout();
+			}
+
+			loadCss(cssUrl);
+
+			// For some reason dynamically loading with defer attribute doesn't result in the expected behavior, the below code does
+			loadScripts(katexScripts).then(() => {
+				if( deck.isReady() ) {
+					renderMath();
+				}
+				else {
+					deck.on( 'ready', renderMath.bind( this ) );
+				}
+			});
+
+		}
+	}
+
+};