看一个例子
$('#conten').click(function(){ //this是被点击的#conten var that =this; $('.conten').each(function(){ //this是.conten循环中当前的对象 //that仍是刚才被点击我的#conten }) })
this对象在程序中随时会改变,而var that = this之后,that不会改变,仍然指向之前的this,这样就不会找不到原来的对象
tab.prototype.init = function(){ for(var i=0,len =this.span.length;i<len;i++){ var that = this; that.span[i].index =i; that.span[i].onclick = function(){ that.show(this.index); } } this.show(1); }
这个例子中,如果将that.show(this.index) 改为 this.show(this.index),此时 this.show中this指向that.span[i],此时会因为找不到that.span[i]而报错。而改成that.show(this,index),此时,that因为前面申明 var that =this,that指向外层。
理解尚不到位我再查查资料。。。。。。