Keep Markup: Added drop-tokens option class (#3166)

PrismJS · Nov 3, 2021 · b679cfe · b679cfe
1 parent 22d0c6b
commit b679cfe
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Showing 4 changed files with 66 additions and 18 deletions.
diff --git a/plugins/keep-markup/index.html b/plugins/keep-markup/index.html
@@ -27,7 +27,7 @@
 	<script>var _gaq = [['_setAccount', 'UA-33746269-1'], ['_trackPageview']];</script>
 	<script src="https://www.google-analytics.com/ga.js" async></script>
 </head>
-<body>
+<body class="language-none">
 
 <header data-plugin-header="keep-markup"></header>
 
@@ -39,6 +39,12 @@ <h1>How to use</h1>
 
 	<p>However, you can deactivate the plugin for certain code element by adding the <code>no-keep-markup</code> class to it. You can also deactivate the plugin for the whole page by adding the <code>no-keep-markup</code> class to the body of the page and then selectively activate it again by adding the <code>keep-markup</code> class to code elements.</p>
 
+	<h2>Double highlighting</h2>
+
+	<p>Some plugins (e.g. <a href="plugins/autoloader">Autoloader</a>) need to re-highlight code blocks. This is a problem for Keep Markup because it will keep the markup of the first highlighting pass resulting in a lot of unnecessary DOM nodes and causing problems for themes and other plugins.</p>
+
+	<p>This problem can be fixed by adding a <code>drop-tokens</code> class to a code block or any of its ancestors. If <code>drop-tokens</code> is present, Keep Markup will ignore all <code class="language-css">span.token</code> elements created by Prism.</p>
+
 	<h1>Examples</h1>
 
 	<p>The following source code</p>

diff --git a/plugins/keep-markup/prism-keep-markup.js b/plugins/keep-markup/prism-keep-markup.js
@@ -15,31 +15,53 @@
 			return;
 		}
 
+		var dropTokens = Prism.util.isActive(env.element, 'drop-tokens', false);
+		/**
+		 * Returns whether the given element should be kept.
+		 *
+		 * @param {HTMLElement} element
+		 * @returns {boolean}
+		 */
+		function shouldKeep(element) {
+			if (dropTokens && element.nodeName.toLowerCase() === 'span' && element.classList.contains('token')) {
+				return false;
+			}
+			return true;
+		}
+
 		var pos = 0;
 		var data = [];
-		var f = function (elt, baseNode) {
-			var o = {};
-			if (!baseNode) {
-				// Clone the original tag to keep all attributes
-				o.clone = elt.cloneNode(false);
-				o.posOpen = pos;
-				data.push(o);
+		function processElement(element) {
+			if (!shouldKeep(element)) {
+				// don't keep this element and just process its children
+				processChildren(element);
+				return;
 			}
-			for (var i = 0, l = elt.childNodes.length; i < l; i++) {
-				var child = elt.childNodes[i];
+
+			var o = {
+				// Clone the original tag to keep all attributes
+				clone: element.cloneNode(false),
+				posOpen: pos
+			};
+			data.push(o);
+
+			processChildren(element);
+
+			o.posClose = pos;
+		}
+		function processChildren(element) {
+			for (var i = 0, l = element.childNodes.length; i < l; i++) {
+				var child = element.childNodes[i];
 				if (child.nodeType === 1) { // element
-					f(child);
+					processElement(child);
 				} else if (child.nodeType === 3) { // text
 					pos += child.data.length;
 				}
 			}
-			if (!baseNode) {
-				o.posClose = pos;
-			}
-		};
-		f(env.element, true);
+		}
+		processChildren(env.element);
 
-		if (data && data.length) {
+		if (data.length) {
 			// data is an array of all existing tags
 			env.keepMarkup = data;
 		}

diff --git a/plugins/keep-markup/prism-keep-markup.min.js b/plugins/keep-markup/prism-keep-markup.min.js
diff --git a/tests/plugins/keep-markup/test.js b/tests/plugins/keep-markup/test.js
@@ -4,6 +4,7 @@ const { createScopedPrismDom } = require('../../helper/prism-dom-util');
 
 describe('Keep Markup', function () {
 	const { Prism, document } = createScopedPrismDom(this, {
+		languages: 'javascript',
 		plugins: 'keep-markup'
 	});
 
@@ -42,6 +43,25 @@ describe('Keep Markup', function () {
 		keepMarkup(`xy<a>a</a>`);
 	});
 
+	it('should support double highlighting', function () {
+		const pre = document.createElement('pre');
+		pre.className = 'language-javascript drop-tokens';
+		pre.innerHTML = '<code>var <mark>a = 42</mark>;</code>';
+		const code = pre.childNodes[0];
+		const initial = code.innerHTML;
+
+		Prism.highlightElement(code);
+		const firstPass = code.innerHTML;
+
+		Prism.highlightElement(code);
+		const secondPass = code.innerHTML;
+
+		// check that we actually did some highlighting
+		assert.notStrictEqual(initial, firstPass);
+		// check that the highlighting persists
+		assert.strictEqual(firstPass, secondPass);
+	});
+
 	// The markup is removed if it's the last element and the element's name is a single letter: a(nchor), b(old), i(talic)...
 	// https://github.com/PrismJS/prism/issues/1618
 	/*