关于使用js为Dom动态添加事件的讨论

[BoolYang]

程序如下：

var addEvent = function(obj,eventType,evtFun){
        if(document.addEventListener){
            obj.addEventListener(eventType,evtFun,false);
        }
        else if(document.attachEvent){
            obj.attachEvent("on"+eventType,evtFun);
        }
    };
var $G = function(a){return document.getElementById(a);};
var TestClass = function(){
        this.items = ['id1','id2','id3','id4'];
        this.init();  
    };
    TestClass.prototype.init = function(){
        for(var i in this.items){
            document.write('<div id='+this.items[i]+'>'+this.items[i]+'</div>');
        }
        var obj = this;
        for(var i in this.items){
            var item = this.items[i];
            addEvent($G(item),'click',function(){obj.click(item);});
        }
    };
    TestClass.prototype.click= function(a){
        alert(a);//这里总是输出id4
    };
var test = new TestClass();

以上代码在ie7与ff 3.0中点击四个div均输出为:id4，而本意是想点id1的div输出为：id1，点id2的div输出为：id2 ...　请问高手上面的代码的问题在什么地方？

改为以下代码后可输出想要的结果，但还是不明白为什么上面的代码会有问题呢？

var addEvent = function(obj,eventType,evtFun){
        if(document.addEventListener){
            obj.addEventListener(eventType,evtFun,false);
        }
        else if(document.attachEvent){
            obj.attachEvent("on"+eventType,evtFun);
        }
    };
var $G = function(a){return document.getElementById(a);};
var TestClass = function(){
        this.items = ['id1','id2','id3','id4'];
        this.init();  
    };
    TestClass.prototype.init = function(){
        for(var i in this.items){
            document.write('<div id='+this.items[i]+'>'+this.items[i]+'</div>');
        }
        for(var i in this.items){
            var item = this.items[i];
            this.addClick(item);
        }
    };
    TestClass.prototype.addClick= function(a){
        var obj = this;
        addEvent($G(a),'click',function(){obj.click(a);});
    };
    TestClass.prototype.click= function(a){
        alert(a);
    };
    var test = new TestClass();

[neo_yoho]

闭包
http://topic.csdn.net/u/20081111/11/b4c4e0ac-f0a8-49b6-867f-a37205cc4dd8.html

[wangliangatleiden]

同意楼上，是闭包问题.

for(var i in this.items){
            var item = this.items[i];//这里的item只是对this.items[i]的一个引用，当执行到最一个item[i]的时候，所有的item都指向最后一个item[i]
            addEvent($G(item),'click',function(){this.click(item);});
        }

[wxnet2008]

for(var i in this.items){
var item = this.items[i];
addEvent($G(item),'click',function(){obj.click(item);});
}

改成
for(var i in this.items){
(function(){
var item = this.items[i];
addEvent($G(item),'click',function(){obj.click(item);});
})();

}

[wxnet2008]

抱歉..
for(var i in this.items){
(function(){
var item = obj.items[i];
addEvent($G(item),'click',function(){obj.click(item);});
})();