add @burgerga's math plugin with MathJax2, MathJax3 and KaTeX support h…

…akimel#2559

examples/math.html

@@ -182,8 +182,7 @@ <h3>TeX Macros</h3>
 				history: true,
 				transition: 'linear',
 
-				math: {
-					// mathjax: 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js',
+				mathjax2: {
 					config: 'TeX-AMS_HTML-full',
 					TeX: {
 						Macros: {
@@ -193,7 +192,13 @@ <h3>TeX Macros</h3>
 					}
 				},
 
-				plugins: [ RevealMath ]
+				// There are three typesetters available
+				// RevealMath.MathJax2 (default)
+				// RevealMath.MathJax3
+				// RevealMath.KaTeX
+				//
+				// More info at https://revealjs.com/math/
+				plugins: [ RevealMath.MathJax2 ]
 			});
 		</script>
 

plugin/math/katex.js

@@ -0,0 +1,87 @@
+/**
+ * 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: false},
+			{left: '$$', right: '$$', display: true},
+			{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);
+
+			loadCss(cssUrl);
+
+			// For some reason dynamically loading with defer attribute doesn't result in the expected behavior, the below code does
+			loadScripts(katexScripts).then(() => {
+				renderMathInElement(document.body, katexOptions);
+				deck.layout();
+			});
+
+		}
+	}
+
+};

plugin/math/mathjax2.js

@@ -0,0 +1,89 @@
+/**
+ * A plugin which enables rendering of math equations inside
+ * of reveal.js slides. Essentially a thin wrapper for MathJax.
+ *
+ * @author Hakim El Hattab
+ */
+export const MathJax2 = () => {
+
+	// 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: 'mathjax2',
+
+		init: function( reveal ) {
+
+			deck = reveal;
+
+			let revealOptions = deck.getConfig().mathjax2 || deck.getConfig().math || {};
+
+			let options = { ...defaultOptions, ...revealOptions };
+			let mathjax = options.mathjax || 'https://cdn.jsdelivr.net/npm/mathjax@2/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 ] );
+
+				} );
+
+			} );
+
+		}
+	}
+
+};

plugin/math/mathjax3.js

@@ -0,0 +1,77 @@
+/**
+ * A plugin which enables rendering of math equations inside
+ * of reveal.js slides. Essentially a thin wrapper for MathJax 3
+ *
+ * @author Hakim El Hattab
+ * @author Gerhard Burger
+ */
+export const MathJax3 = () => {
+
+    // The reveal.js instance this plugin is attached to
+    let deck;
+
+    let defaultOptions = {
+        tex: {
+            inlineMath: [ [ '$', '$' ], [ '\\(', '\\)' ]  ]
+        },
+        options: {
+            skipHtmlTags: [ 'script', 'noscript', 'style', 'textarea', 'pre' ]
+        },
+        startup: {
+            ready: () => {
+                MathJax.startup.defaultReady();
+                MathJax.startup.promise.then(() => {
+                    Reveal.layout();
+                });
+            }
+        }
+    };
+
+    function loadScript( url, callback ) {
+
+        let script = document.createElement( 'script' );
+        script.type = "text/javascript"
+        script.id = "MathJax-script"
+        script.src = url;
+        script.async = true
+
+        // Wrapper for callback to make sure it only fires once
+        script.onload = () => {
+            if (typeof callback === 'function') {
+                callback.call();
+                callback = null;
+            }
+        };
+
+        document.head.appendChild( script );
+
+    }
+
+    return {
+        id: 'mathjax3',
+        init: function(reveal) {
+
+            deck = reveal;
+
+            let revealOptions = deck.getConfig().mathjax3 || {};
+            let options = {...defaultOptions, ...revealOptions};
+            options.tex = {...defaultOptions.tex, ...revealOptions.tex}
+            options.options = {...options.options, ...defaultOptions.options}
+            options.startup = {...defaultOptions.startup, ...revealOptions.startup}
+
+            let url = options.mathjax || 'https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js';
+            options.mathjax = null;
+
+            window.MathJax = options;
+
+            loadScript( url, function() {
+                // Reprocess equations in slides when they turn visible
+                Reveal.addEventListener( 'slidechanged', function( event ) {
+                    MathJax.typeset();
+                } );
+            } );
+
+        }
+    }
+
+};