div
1、新建一个层，点击层，希望层的背景色在蓝色和红色之间切换。
<script type="text/javascript"> function addEVent(obj,type,fn){ var saved=null; //判断是否之前有事件，如果有，保存下来 if(typeof obj['on'+type]=='function'){ saved=obj['on'+type]; } //执行 obj['on'+type]=function(){ if(saved)saved(); fn.call(this); }; } addEVent(window,'load',function(){ var box=document.getElementById('box'); addEVent(box,'click',toBlue); }); function toBlue(){ this.className='blue'; addEVent(this,'click',toRed); } function toRed(){ this.className='red'; addEVent(this,'click',toBlue); } </script>
<body> <div id="box" class="red">div</div> </body>
<style type="text/css">
.red{
100px;
height:100px;
background:red;
}
.blue{
100px;
height:100px;
background:blue;
}
</style>