原来的代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>导航菜单</title>
<style type="text/css">
* { margin: 0; padding: 0; font-size: 14px; }
a { color: #333; text-decoration: none }
ul { list-style: none; height: 30px; border-bottom: 5px solid #F60; margin-top: 20px; padding-left: 50px; }
ul li { float: left }
ul li a { display: block; height: 30px; text-align: center; line-height: 30px; width:120px; background: #efefef; margin-left: 1px; }
a.on, a:hover { background: #F60; color: #fff; }
</style>
<script>
window.onload=function(){
var aA=document.getElementsByTagName('a');
for(var i=0; i<aA.length; i++){
aA[i].onmouseover=function(){
var This=this;
clearInterval(This.time);
This.time=setInterval(function(){
This.style.width=This.offsetWidth+8+"px";
if(This.offsetWidth>=160)
clearInterval(This.time);
},30)
}
aA[i].onmouseout=function(){
clearInterval(this.time);
var This=this;
this.time=setInterval(function(){
This.style.width=This.offsetWidth-8+"px";
if(This.offsetWidth<=120){
This.style.width='120px';
clearInterval(This.time);
}
},30)
}
}
}
</script>
</head>
<body>
<ul>
<li><a class="on" href="#">首 页</a></li>
<li><a href="#">新闻快讯</a></li>
<li><a href="#">产品展示</a></li>
<li><a href="#">售后服务</a></li>
<li><a href="#">联系我们</a></li>
</ul>
</body>
</html>JS部分封装后：
<script>
window.onload=function(){
wrap('a');
}
function wrap(obj){
var x=obj;
var aA=document.getElementsByTagName('x');
for(var i=0; i<aA.length; i++){
aA[i].onmouseover=function(){
var This=this;
clearInterval(This.time);
This.time=setInterval(function(){
This.style.width=This.offsetWidth+8+"px";
if(This.offsetWidth>=160)
clearInterval(This.time);
},30)
}
aA[i].onmouseout=function(){
clearInterval(this.time);
var This=this;
this.time=setInterval(function(){
This.style.width=This.offsetWidth-8+"px";
if(This.offsetWidth<=120){
This.style.width='120px';
clearInterval(This.time);
}
},30)
}
}
}
</script>__End