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Unified Diff: chrome/browser/resources/touch_ntp/eventtracker.js

Issue 6661024: Use a specialized new tab page in TOUCH_UI builds (Closed) Base URL: http://git.chromium.org/git/chromium.git@trunk
Patch Set: Fix some indentation issues and enable gjslist --strict mode to catch them automatically Created 9 years, 9 months ago
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Index: chrome/browser/resources/touch_ntp/eventtracker.js
diff --git a/chrome/browser/resources/touch_ntp/eventtracker.js b/chrome/browser/resources/touch_ntp/eventtracker.js
new file mode 100644
index 0000000000000000000000000000000000000000..bb76f5e920b772f95d80302e1e41fefb1ae3a89a
--- /dev/null
+++ b/chrome/browser/resources/touch_ntp/eventtracker.js
@@ -0,0 +1,99 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/** @fileoverview EventTracker is a simple class that manages the addition and
+ * removal of DOM event listeners. In particular, it keeps track of all
+ * listeners that have been added and makes it easy to remove some or all of
+ * them without requiring all the information again. This is particularly
+ * handy when the listener is a generated function such as a lambda or the
+ * result of calling Function.bind. The goal of this class is to make it
+ * easier to avoid memory leaks caused by DOM<->JS cycles - removing event
+ * listeners breakes the DOM->JS part of the cycle.
+ */
+
+// Use an anonymous function to enable strict mode just for this file (which
+// will be concatenated with other files when embedded in Chrome)
+var EventTracker = (function() {
+ 'use strict';
+
+ /**
+ * Create an EventTracker to track a set of events.
+ * EventTracker instances are typically tied 1:1 with other objects or
+ * DOM elements whose listeners should be removed when the object is disposed
+ * or the corresponding elements are removed from the DOM.
+ * @constructor
+ */
+ function EventTracker() {
+ /**
+ * @type {Array.<EventTracker.Entry>}
+ * @private
+ */
+ this.listeners_ = [];
+ }
+
+ /**
+ * The type of the internal tracking entry.
+ * @typedef {{node: !Node,
+ * eventType: string,
+ * listener: Function,
+ * capture: boolean}}
+ */
+ EventTracker.Entry;
+
+ EventTracker.prototype = {
+ /**
+ * Add an event listener - replacement for Node.addEventListener.
+ * @param {!Node} node The DOM node to add a listener to.
+ * @param {string} eventType The type of event to subscribe to.
+ * @param {Function} listener The listener to add.
+ * @param {boolean} capture Whether to invoke during the capture phase.
+ */
+ add: function(node, eventType, listener, capture) {
+ var h = {
+ node: node,
+ eventType: eventType,
+ listener: listener,
+ capture: capture
+ };
+ this.listeners_.push(h);
+ node.addEventListener(eventType, listener, capture);
+ },
+
+ /**
+ * Remove any specified event listeners added with this EventTracker.
+ * @param {!Node} node The DOM node to remove a listener from.
+ * @param {string} eventType The type of event to remove.
+ */
+ remove: function(node, eventType) {
+ this.listeners_ = this.listeners_.filter(function(h) {
+ if (h.node == node && h.eventType == eventType) {
+ EventTracker.removeEventListener_(h);
+ return false;
+ }
+ return true;
+ });
+ },
+
+ /**
+ * Remove all event listeners added with this EventTracker.
+ */
+ removeAll: function() {
+ this.listeners_.forEach(EventTracker.removeEventListener_);
+ this.listeners_ = [];
+ }
+ };
+
+ /**
+ * Remove a single event listener given it's tracker entry. It's up to the
+ * caller to ensure the entry is removed from listeners_.
+ * @param {EventTracker.Entry} h The entry describing the listener to remove.
+ * @private
+ */
+ EventTracker.removeEventListener_ = function(h) {
+ h.node.removeEventListener(h.eventType, h.listener, h.capture);
+ };
+
+ return EventTracker;
+})();
+
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