Toolbar: data-toolbar-order is now inherited (#2205)

The `data-toolbar-order` property is now inherited allowing for custom orderings/selections on an per-element basis.

plugins/toolbar/index.html

@@ -35,6 +35,8 @@ <h1>How to use</h1>
 
 	<pre><code>&lt;template id=&quot;my-label-button&quot;&gt;&lt;button onclick=&quot;console.log('This is an inline-handler');&quot;&gt;My button&lt;/button&gt;&lt;/template&gt;</code></pre>
 
+	<h2>Registering buttons</h2>
+
 	<p>For more flexibility, the Toolbar exposes a JavaScript function that can be used to register new buttons or labels to the Toolbar,
 		<code>Prism.plugins.toolbar.registerButton</code>.</p>
 
@@ -78,9 +80,17 @@ <h1>How to use</h1>
 
 	<p>The above function creates the Select Code button you see, and when you click it, the code gets highlighted.</p>
 
+	<h2>Ordering buttons</h2>
+
 	<p>By default, the buttons will be added to the code snippet in the order they were registered. If more control over
-		the order is needed, an HTML attribute can be added to the <code>body</code> tag with a comma-separated string indicating the
-		order.</p>
+		the order is needed, the <code>data-toolbar-order</code> attribute can be used. Given a comma-separated list of button names, it will ensure that these buttons will be displayed in the given order. <br>
+		Buttons not listed will not be displayed. This means that buttons can be disabled using this technique.</p>
+
+	<p>Example: The "Hello World!" button will appear before the "Select Code" button and the custom label button will not be displayed.</p>
+
+	<pre data-toolbar-order="hello-world,select-code" data-label="Hello World!"><code>&lt;pre data-toolbar-order="hello-world,select-code" data-label="Hello World!">&lt;code>&lt;/code>&lt;/pre></code></pre>
+
+	<p>The <code>data-toolbar-order</code> attribute is inherited, so you can define the button order for the whole document by adding the attribute to the <code>body</code> of the page.</p>
 
 	<pre><code>&lt;body data-toolbar-order="select-code,hello-world,label"&gt;</code></pre>
 </section>

plugins/toolbar/prism-toolbar.js

@@ -63,6 +63,27 @@
 		callbacks.push(map[key] = callback);
 	};
 
+	/**
+	 * Returns the callback order of the given element.
+	 *
+	 * @param {HTMLElement} element
+	 * @returns {string[] | undefined}
+	 */
+	function getOrder(element) {
+		while (element) {
+			var order = element.getAttribute('data-toolbar-order');
+			if (order != null) {
+				order = order.trim();
+				if (order.length) {
+					return order.split(/\s*,\s*/g);
+				} else {
+					return [];
+				}
+			}
+			element = element.parentElement;
+		}
+	}
+
 	/**
 	 * Post-highlight Prism hook callback.
 	 *
@@ -81,22 +102,25 @@
 		}
 
 		// Create wrapper for <pre> to prevent scrolling toolbar with content
-		var wrapper = document.createElement("div");
-		wrapper.classList.add("code-toolbar");
+		var wrapper = document.createElement('div');
+		wrapper.classList.add('code-toolbar');
 		pre.parentNode.insertBefore(wrapper, pre);
 		wrapper.appendChild(pre);
 
 		// Setup the toolbar
 		var toolbar = document.createElement('div');
 		toolbar.classList.add('toolbar');
 
-		if (document.body.hasAttribute('data-toolbar-order')) {
-			callbacks = document.body.getAttribute('data-toolbar-order').split(',').map(function(key) {
+		// order callbacks
+		var elementCallbacks = callbacks;
+		var order = getOrder(env.element);
+		if (order) {
+			elementCallbacks = order.map(function (key) {
 				return map[key] || noop;
 			});
 		}
 
-		callbacks.forEach(function(callback) {
+		elementCallbacks.forEach(function(callback) {
 			var element = callback(env);
 
 			if (!element) {