Javascript教程：关于内存泄漏问题(3)
http://talideon.com/weblog/2005/03/js-memory-leaks.cfm 一文中的方法类似：
/*
* EventManager.js
* by Keith Gaughan
*
* This allows event handlers to be registered unobtrusively, and cleans
* them up on unload to prevent memory leaks.
*
* Copyright (c) Keith Gaughan, 2005.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Common Public License v1.0
* (CPL) which accompanies this distribution, and is available at
* http://www.opensource.org/licenses/cpl.php
*
* This software is covered by a modified version of the Common Public License
* (CPL), where Keith Gaughan is the Agreement Steward, and the licensing
* agreement is covered by the laws of the Republic of Ireland.
*/
// For implementations that don't include the push() methods for arrays.
if(!Array.prototype.push){
Array.prototype.push=function(elem){
this[this.length]=elem;
}
}
var EventManager={
_registry: null,
Initialise: function(){
if(this._registry==null){
this._registry=[];
// Register the cleanup handler on page unload.
EventManager.Add(window,"unload" ,this.CleanUp);
}
},
/*
* Registers an event and handler with the manager.
*
* @param obj Object handler will be attached to.
* @param type Name of event handler responds to.
* @param fn Handler function.
* @param useCapture Use event capture. False by default.
* If you don't understand this, ignore it.
*
* @return True if handler registered, else false.
*/
Add: function(obj, type, fn, useCapture){
this.Initialise();
// If a string was passed in, it's an id.
if(typeof obj=="string"){
obj = document.getElementById(obj);
}
if(obj==null || fn==null){
return false ;
}
// Mozilla/W3C listeners?
if(obj.addEventListener){
obj.addEventListener(type, fn, useCapture);
this._registry.push({obj: obj, type: type, fn: fn, useCapture: useCapture});
return true ;
}
// IE-style listeners?
if(obj.attachEvent && obj.attachEvent("on" + type,fn)){
this._registry.push({obj: obj, type: type, fn: fn, useCapture: false });
return true ;
}
return false ;
},
/* *
* Cleans up all the registered event handlers.
*/
CleanUp: function(){
for(var i=0;i<EventManager._registry.length;i++){
with(EventManager._registry[i]) {
// Mozilla/W3C listeners?
if(obj.removeEventListener) {
obj.removeEventListener(type, fn, useCapture);
}
else if(obj.detachEvent){// IE-style listeners?
obj.detachEvent("on"+type,fn);
}
}
}
// Kill off the registry itself to get rid of the last remaining
// references.
EventManager._registry = null ;
}
};
使用起来也很简单：
<html>
<head>
<script type=text/javascript src=EventManager.js></script>
<script type=text/javascript>
function onLoad(){
EventManager.Add(document.getElementById(testCase),click,hit);
return true;
}
function hit(evt) {
alert(click);
}
</script>
</head>
<body onload='javascript: onLoad();'>
<div id='testCase' style='width:100%; height: 100%; background-color: yellow;'>
<h1>Click me!</h1>
</div>
</body>
</html>
google map api同样提供了一个类似的函数用在页面的unload事件中，解决Closure带来的内存泄露问题。
当然，如果你不嫌麻烦，你也可以为每个和native object有关的就阿vascript object编写一个destoryMemory函数，用来手动调用，从而手动解除Dom对象的事件绑定。
还有一种就是不要那么OO,抛弃Dom的一些特性，用innerHTML代替appendChild，避开循环引用。详细见http://birdshome.cnblogs.com/archive/2005/02/16/104967.html中的讨论贴。