feat: Improve perf of axe.run [WWD-1821]

lib/checks/aria/required-children.js

@@ -30,7 +30,7 @@ function ariaOwns(nodes, role) {
 		if (nodes[index] === null) {
 			continue;
 		}
-		let virtualTree = axe.utils.getNodeFromTree(axe._tree[0], nodes[index]);
+		let virtualTree = axe.utils.getNodeFromTree(nodes[index]);
 		if (owns(nodes[index], virtualTree, role, true)) {
 			return true;
 		}

lib/checks/aria/required-parent.js

@@ -73,7 +73,7 @@ var owners = getAriaOwners(node);
 if (owners) {
 	for (var i = 0, l = owners.length; i < l; i++) {
 		missingParents = getMissingContext(
-			axe.utils.getNodeFromTree(axe._tree[0], owners[i]),
+			axe.utils.getNodeFromTree(owners[i]),
 			missingParents,
 			true
 		);

lib/commons/aria/get-owned-virtual.js

@@ -16,7 +16,7 @@ aria.getOwnedVirtual = function getOwned({ actualNode, children }) {
 
 	return dom.idrefs(actualNode, 'aria-owns').reduce((ownedElms, element) => {
 		if (element) {
-			const virtualNode = axe.utils.getNodeFromTree(axe._tree[0], element);
+			const virtualNode = axe.utils.getNodeFromTree(element);
 			ownedElms.push(virtualNode);
 		}
 		return ownedElms;

lib/commons/aria/is-accessible-ref.js

@@ -1,13 +1,24 @@
 /* global aria, axe, dom */
-function findDomNode(node, functor) {
-	if (functor(node)) {
-		return node;
+const idRefsRegex = /^idrefs?$/;
+
+function cacheIdRefs(node, refAttrs) {
+	if (node.hasAttribute) {
+		if (node.nodeName.toUpperCase() === 'LABEL' && node.hasAttribute('for')) {
+			axe._cache.idRefs[node.getAttribute('for')] = 1;
+		}
+
+		refAttrs
+			.filter(attr => node.hasAttribute(attr))
+			.forEach(attr => {
+				const attrValue = node.getAttribute(attr);
+				axe.utils.tokenList(attrValue).forEach(id => {
+					axe._cache.idRefs[id] = 1;
+				});
+			});
 	}
+
 	for (let i = 0; i < node.children.length; i++) {
-		const out = findDomNode(node.children[i], functor);
-		if (out) {
-			return out;
-		}
+		cacheIdRefs(node.children[i], refAttrs);
 	}
 }
 
@@ -22,34 +33,18 @@ aria.isAccessibleRef = function isAccessibleRef(node) {
 	root = root.documentElement || root; // account for shadow roots
 	const id = node.id;
 
-	// Get all idref(s) attributes on the lookup table
-	const refAttrs = Object.keys(aria.lookupTable.attributes).filter(attr => {
-		const { type } = aria.lookupTable.attributes[attr];
-		return /^idrefs?$/.test(type);
-	});
+	// because axe.commons is not available in axe.utils, we can't do
+	// this caching when we build up the virtual tree
+	if (!axe._cache.idRefs) {
+		axe._cache.idRefs = {};
+		// Get all idref(s) attributes on the lookup table
+		const refAttrs = Object.keys(aria.lookupTable.attributes).filter(attr => {
+			const { type } = aria.lookupTable.attributes[attr];
+			return idRefsRegex.test(type);
+		});
 
-	// Find the first element that IDREF(S) the node
-	let refElm = findDomNode(root, elm => {
-		if (elm.nodeType !== 1) {
-			// Elements only
-			return;
-		}
-		if (
-			elm.nodeName.toUpperCase() === 'LABEL' &&
-			elm.getAttribute('for') === id
-		) {
-			return true;
-		}
-		// See if there are any aria attributes that reference the node
-		return refAttrs
-			.filter(attr => elm.hasAttribute(attr))
-			.some(attr => {
-				const attrValue = elm.getAttribute(attr);
-				if (aria.lookupTable.attributes[attr].type === 'idref') {
-					return attrValue === id;
-				}
-				return axe.utils.tokenList(attrValue).includes(id);
-			});
-	});
-	return typeof refElm !== 'undefined';
+		cacheIdRefs(root, refAttrs);
+	}
+
+	return axe._cache.idRefs[id] === 1;
 };

lib/commons/aria/label-virtual.js

@@ -17,7 +17,7 @@ aria.labelVirtual = function({ actualNode }) {
 		ref = dom.idrefs(actualNode, 'aria-labelledby');
 		candidate = ref
 			.map(function(thing) {
-				const vNode = axe.utils.getNodeFromTree(axe._tree[0], thing);
+				const vNode = axe.utils.getNodeFromTree(thing);
 				return vNode ? text.visibleVirtual(vNode, true) : '';
 			})
 			.join(' ')
@@ -49,6 +49,6 @@ aria.labelVirtual = function({ actualNode }) {
  * @return {Mixed} String of visible text, or `null` if no label is found
  */
 aria.label = function(node) {
-	node = axe.utils.getNodeFromTree(axe._tree[0], node);
+	node = axe.utils.getNodeFromTree(node);
 	return aria.labelVirtual(node);
 };

lib/commons/dom/find-up.js

@@ -12,7 +12,7 @@
  */
 dom.findUp = function(element, target) {
 	return dom.findUpVirtual(
-		axe.utils.getNodeFromTree(axe._tree[0], element),
+		axe.utils.getNodeFromTree(element),
 		target
 	);
 };

lib/commons/dom/has-content-virtual.js

@@ -59,7 +59,7 @@ dom.hasContentVirtual = function(elm, noRecursion) {
  * @return {Boolean}
  */
 dom.hasContent = function hasContent(elm, noRecursion) {
-	elm = axe.utils.getNodeFromTree(axe._tree[0], elm);
+	elm = axe.utils.getNodeFromTree(elm);
 	return dom.hasContentVirtual(elm, noRecursion);
 };
 

lib/commons/dom/is-in-text-block.js

@@ -17,7 +17,7 @@ function getBlockParent(node) {
 	while (parentBlock && !isBlock(parentBlock)) {
 		parentBlock = dom.getComposedParent(parentBlock);
 	}
-	return axe.utils.getNodeFromTree(axe._tree[0], parentBlock);
+	return axe.utils.getNodeFromTree(parentBlock);
 }
 
 /**

lib/commons/dom/is-visible.js

@@ -33,7 +33,9 @@ function isClipped(clip) {
  */
 dom.isVisible = function(el, screenReader, recursed) {
 	'use strict';
-	var style, nodeName, parent;
+	const node = axe.utils.getNodeFromTree(el);
+	const cacheName = 'isVisible' + (screenReader ? 'ScreenReader' : '');
+	let style, nodeName, parent, isVisible;
 
 	// 9 === Node.DOCUMENT
 	if (el.nodeType === 9) {
@@ -45,6 +47,10 @@ dom.isVisible = function(el, screenReader, recursed) {
 		el = el.host; // grab the host Node
 	}
 
+	if (node && typeof node[cacheName] !== 'undefined') {
+		return node[cacheName];
+	}
+
 	style = window.getComputedStyle(el, null);
 	if (style === null) {
 		return false;
@@ -68,8 +74,14 @@ dom.isVisible = function(el, screenReader, recursed) {
 
 	parent = el.assignedSlot ? el.assignedSlot : el.parentNode;
 	if (parent) {
-		return dom.isVisible(parent, screenReader, true);
+		isVisible = dom.isVisible(parent, screenReader, true);
+	} else {
+		isVisible = false;
 	}
 
-	return false;
+	if (node) {
+		node[cacheName] = isVisible;
+	}
+
+	return isVisible;
 };

lib/commons/text/accessible-text-virtual.js

@@ -11,7 +11,7 @@
  * @return {string}
  */
 text.accessibleText = function accessibleText(element, context) {
-	let virtualNode = axe.utils.getNodeFromTree(axe._tree[0], element); // throws an exception on purpose if axe._tree not correct
+	let virtualNode = axe.utils.getNodeFromTree(element); // throws an exception on purpose if axe._tree not correct
 	return text.accessibleTextVirtual(virtualNode, context);
 };
 

lib/commons/text/label-virtual.js

@@ -48,6 +48,6 @@ text.labelVirtual = function(node) {
  * @return {Mixed} String of visible text, or `null` if no label is found
  */
 text.label = function(node) {
-	node = axe.utils.getNodeFromTree(axe._tree[0], node);
+	node = axe.utils.getNodeFromTree(node);
 	return text.labelVirtual(node);
 };

lib/commons/text/visible-virtual.js

@@ -41,6 +41,6 @@ text.visibleVirtual = function(element, screenReader, noRecursing) {
  * @return {String}
  */
 text.visible = function(element, screenReader, noRecursing) {
-	element = axe.utils.getNodeFromTree(axe._tree[0], element);
+	element = axe.utils.getNodeFromTree(element);
 	return text.visibleVirtual(element, screenReader, noRecursing);
 };

lib/core/base/context.js

@@ -134,7 +134,7 @@ function parseSelectorArray(context, type) {
 			//eslint no-loop-func:0
 			result = result.concat(
 				nodeList.map(node => {
-					return axe.utils.getNodeFromTree(context.flatTree[0], node);
+					return axe.utils.getNodeFromTree(node);
 				})
 			);
 			break;
@@ -146,15 +146,15 @@ function parseSelectorArray(context, type) {
 				//eslint no-loop-func:0
 				result = result.concat(
 					nodeList.map(node => {
-						return axe.utils.getNodeFromTree(context.flatTree[0], node);
+						return axe.utils.getNodeFromTree(node);
 					})
 				);
 			}
 		} else if (item instanceof Node) {
 			if (item.documentElement instanceof Node) {
 				result.push(context.flatTree[0]);
 			} else {
-				result.push(axe.utils.getNodeFromTree(context.flatTree[0], item));
+				result.push(axe.utils.getNodeFromTree(item));
 			}
 		}
 	}

lib/core/imports/index.js

@@ -14,6 +14,12 @@ if (!('Promise' in window)) {
 	require('es6-promise').polyfill();
 }
 
+/**
+ * Polyfill `WeakMap`
+ * Reference: https://github.com/polygonplanet/weakmap-polyfill
+ */
+require('weakmap-polyfill');
+
 /**
  * Namespace `axe.imports` which holds required external dependencies
  *

lib/core/public/run-rules.js

@@ -3,6 +3,7 @@
 
 // Clean up after resolve / reject
 function cleanup() {
+	axe._cache = undefined;
 	axe._tree = undefined;
 	axe._selectorData = undefined;
 }
@@ -18,6 +19,10 @@ function cleanup() {
 function runRules(context, options, resolve, reject) {
 	'use strict';
 	try {
+		axe._cache = {
+			nodeMap: new WeakMap()
+		};
+
 		context = new Context(context);
 		axe._tree = context.flatTree;
 		axe._selectorData = axe.utils.getSelectorData(context.flatTree);

lib/core/utils/flattened-tree.js

@@ -28,10 +28,11 @@ var axe = axe || { utils: {} };
  */
 function virtualDOMfromNode(node, shadowId) {
 	const vNodeCache = {};
-	return {
+	const vNode = {
 		shadowId: shadowId,
 		children: [],
 		actualNode: node,
+		_isHidden: null, // will be populated by axe.utils.isHidden
 		get isFocusable() {
 			if (!vNodeCache._isFocusable) {
 				vNodeCache._isFocusable = axe.commons.dom.isFocusable(node);
@@ -47,6 +48,8 @@ function virtualDOMfromNode(node, shadowId) {
 			return vNodeCache._tabbableElements;
 		}
 	};
+	axe._cache.nodeMap.set(node, vNode);
+	return vNode;
 }
 
 /**
@@ -144,26 +147,13 @@ axe.utils.getFlattenedTree = function(node, shadowId) {
 };
 
 /**
- * Recursively return a single node from a virtual dom tree
+ * Return a single node from the virtual dom tree
  *
- * @param {Object} vNode The flattened, virtual DOM tree
+ * @param {Object} vNode The flattened, virtual DOM tree (deprecated)
  * @param {Node}   node  The HTML DOM node
  */
 axe.utils.getNodeFromTree = function(vNode, node) {
-	var found;
-
-	if (vNode.actualNode === node) {
-		return vNode;
-	}
-	vNode.children.forEach(candidate => {
-		if (found) {
-			return;
-		}
-		if (candidate.actualNode === node) {
-			found = candidate;
-		} else {
-			found = axe.utils.getNodeFromTree(candidate, node);
-		}
-	});
-	return found;
+	// TODO: remove vNode parameter in next major release
+	const el = node || vNode;
+	return axe._cache.nodeMap.get(el);
 };

lib/core/utils/is-hidden.js

@@ -8,7 +8,8 @@
  */
 axe.utils.isHidden = function isHidden(el, recursed) {
 	'use strict';
-	var parent;
+	const node = axe.utils.getNodeFromTree(el);
+	let parent, isHidden;
 
 	// 9 === Node.DOCUMENT
 	if (el.nodeType === 9) {
@@ -20,7 +21,11 @@ axe.utils.isHidden = function isHidden(el, recursed) {
 		el = el.host; // grab the host Node
 	}
 
-	var style = window.getComputedStyle(el, null);
+	if (node && node._isHidden !== null) {
+		return node._isHidden;
+	}
+
+	const style = window.getComputedStyle(el, null);
 
 	if (
 		!style ||
@@ -35,6 +40,14 @@ axe.utils.isHidden = function isHidden(el, recursed) {
 	}
 
 	parent = el.assignedSlot ? el.assignedSlot : el.parentNode;
+	isHidden = axe.utils.isHidden(parent, true);
+
+	// cache the results of the isHidden check on the parent tree
+	// so we don't have to look at the parent tree again for all its
+	// descendants
+	if (node) {
+		node._isHidden = isHidden;
+	}
 
-	return axe.utils.isHidden(parent, true);
+	return isHidden;
 };

lib/rules/color-contrast-matches.js

@@ -53,10 +53,7 @@ if (nodeName === 'LABEL' || nodeParentLabel) {
 	if (nodeParentLabel) {
 		relevantNode = nodeParentLabel;
 		// we need an input candidate from a parent to account for label children
-		relevantVirtualNode = axe.utils.getNodeFromTree(
-			axe._tree[0],
-			nodeParentLabel
-		);
+		relevantVirtualNode = axe.utils.getNodeFromTree(nodeParentLabel);
 	}
 	// explicit label of disabled input
 	let doc = axe.commons.dom.getRootNode(relevantNode);

package.json

@@ -122,7 +122,8 @@
 		"sri-toolbox": "^0.2.0",
 		"standard-version": "^5.0.0",
 		"typescript": "^2.9.2",
-		"uglify-js": "^3.4.4"
+		"uglify-js": "^3.4.4",
+		"weakmap-polyfill": "^2.0.0"
 	},
 	"dependencies": {},
 	"lint-staged": {