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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 /** @fileoverview EventTracker is a simple class that manages the addition and | |
6 * removal of DOM event listeners. In particular, it keeps track of all | |
7 * listeners that have been added and makes it easy to remove some or all of | |
8 * them without requiring all the information again. This is particularly | |
9 * handy when the listener is a generated function such as a lambda or the | |
10 * result of calling Function.bind. The goal of this class is to make it | |
11 * easier to avoid memory leaks caused by DOM<->JS cycles - removing event | |
12 * listeners breakes the DOM->JS part of the cycle. | |
13 */ | |
14 | |
15 // Use an anonymous function to enable strict mode just for this file (which | |
16 // will be concatenated with other files when embedded in Chrome) | |
17 var EventTracker = (function() { | |
18 'use strict'; | |
19 | |
20 /** | |
21 * Create an EventTracker to track a set of events. | |
22 * EventTracker instances are typically tied 1:1 with other objects or | |
23 * DOM elements whose listeners should be removed when the object is disposed | |
24 * or the corresponding elements are removed from the DOM. | |
25 * @constructor | |
26 */ | |
27 function EventTracker() { | |
28 /** | |
29 * @type {Array.<EventTracker.Entry>} | |
30 * @private | |
31 */ | |
32 this.listeners_ = []; | |
33 } | |
34 | |
35 /** | |
36 * The type of the internal tracking entry. | |
37 * @typedef {{node: !Node, | |
38 * eventType: string, | |
39 * listener: Function, | |
40 * capture: boolean}} | |
41 */ | |
42 EventTracker.Entry; | |
43 | |
44 EventTracker.prototype = { | |
45 /** | |
46 * Add an event listener - replacement for Node.addEventListener. | |
47 * @param {!Node} node The DOM node to add a listener to. | |
48 * @param {string} eventType The type of event to subscribe to. | |
49 * @param {Function} listener The listener to add. | |
50 * @param {boolean} capture Whether to invoke during the capture phase. | |
51 */ | |
52 add: function(node, eventType, listener, capture) { | |
53 var h = { | |
54 node: node, | |
55 eventType: eventType, | |
56 listener: listener, | |
57 capture: capture | |
58 }; | |
59 this.listeners_.push(h); | |
60 node.addEventListener(eventType, listener, capture); | |
61 }, | |
62 | |
63 /** | |
64 * Remove any specified event listeners added with this EventTracker. | |
65 * @param {!Node} node The DOM node to remove a listener from. | |
66 * @param {string} eventType The type of event to remove. | |
67 */ | |
68 remove: function(node, eventType) { | |
69 this.listeners_ = this.listeners_.filter(function(h) { | |
70 if (h.node == node && h.eventType == eventType) { | |
71 EventTracker.removeEventListener_(h); | |
72 return false; | |
73 } | |
74 return true; | |
75 }); | |
76 }, | |
77 | |
78 /** | |
79 * Remove all event listeners added with this EventTracker. | |
80 */ | |
81 removeAll: function() { | |
82 this.listeners_.forEach(EventTracker.removeEventListener_); | |
83 this.listeners_ = []; | |
84 } | |
85 }; | |
86 | |
87 /** | |
88 * Remove a single event listener given it's tracker entry. It's up to the | |
89 * caller to ensure the entry is removed from listeners_. | |
90 * @param {EventTracker.Entry} h The entry describing the listener to remove. | |
91 * @private | |
92 */ | |
93 EventTracker.removeEventListener_ = function(h) | |
94 { | |
arv (Not doing code reviews)
2011/03/16 22:55:05
{ before line break
Rick Byers
2011/03/17 16:18:22
Dammit - I keep making this mistake, sorry - old h
| |
95 h.node.removeEventListener(h.eventType, h.listener, h.capture); | |
96 }; | |
97 | |
98 return EventTracker; | |
99 })(); | |
100 | |
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