js有效果，jq就没效果了怎么回事？求大神告知
<%@ page language="java" contentType="text/html; charset=utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!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}
.nav{list-style:none; height:30px; border-bottom:10px solid #F60; margin-top:20px; padding-left:50px;}
.nav li{float:left}
.nav li a{display:block; height:30px;text-align:center; line-height:30px; width:80px; background:#efefef; margin-left:1px;}
.nav li a.on, .nav li a:hover{background:#F60;color:#fff; }
</style>
<script type="text/javascript" src="assets/js/jquery.min.js"></script>
<script>
$(function(){
$('a').hover(
function(){
$(this).stop().animate({"width":"160px"},200);
}
function(){
$(this).stop().animate({"width":"120px"},200);
}
)
})
</script>
<!-- <script>
window.onload=function(){
var oNav=document.getElementsByTagName('ul')[0];
var aA=oNav.getElementsByTagName('a');
for(var i=0; i<aA.length; i++){
aA[i].onmouseover=function(){
if(this.className!="on"){
clearInterval(this.timer);
var This=this;
This.time=setInterval(function(){
This.style.width=This.offsetWidth+8+"px";
if(This.offsetWidth>=120)
clearInterval(This.time);
},30)
}
}
aA[i].onmouseout=function(){
if(this.className!="on"){
clearInterval(this.time);
var This=this;
this.time=setInterval(function(){
This.style.width=This.offsetWidth-8+"px";
if(This.offsetWidth<=80){
This.style.width='80px';
clearInterval(This.time);
}
},30)
}
}
}
}
</script> -->
</head>
<body>
<ul class="nav">
<li><a class="on" href="#">首 页</a></li>
<li><a href="#">关于我们</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>
