原生JavaScript与CSS实现弹性导航菜单

<!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>Js实现菜单弹性菜单</title>
<style type="text/css">
body, ul, ol, dl, dt, dd, h1, h2, h3, h4, h5, p, form { padding: 0; margin: 0; }
li { list-style: none; }
img { border: 0; }
body { font-family: Arial; background: #fff url() repeat-x; }
#header { width: 960px; height: 107px; margin: 0 auto 12px; position: relative; }
#header h1 { padding-top: 15px; float: left; }
#header ul { height: 44px; position: absolute; right: 0; bottom: 0; }
#header .normal, #header .active { float: left; width: 88px; height: 44px; position: relative; z-index: 1; }
#header .normal a, #header .active a { float: left; width: 88px; height: 44px; line-height: 44px; text-align: center; text-decoration: none; font-size: 14px; font-weight: bold; }
#header .active a { color: #fff; }
#header .normal a { color: #999; }
#btn_bg { width: 88px; height: 44px; background: #fb2347 url(); position: absolute; overflow:hidden; left: 608px; bottom: 0; z-index: 2; }
#btn_bg ul { width: 528px; left:-176px; position:absolute; }
</style>
<script type="text/javascript">
var away;
window.onload=function()
{
 var odiv=document.getElementById("btn_bg");
 var oul=odiv.getElementsByTagName("ul")[0];
 var oli=document.getElementById("header").getElementsByTagName("ul")[0].getElementsByTagName("li");
 var i=0;
 for(i=0;i<oli.length;i++)
 {
  oli[i].index=i;
  oli[i].onmouseover=function()
  {
   away=432+88*this.index;
   menuInterval(); 
  };
 };
}
var timer=null;
function menuInterval()
{
 if(timer)
 {
  clearInterval(timer);
 }
 timer=setInterval(menuMove, 30);
}
var step=0;
var l=0;
function menuMove()
{
 var odiv=document.getElementById("btn_bg");
 var oul=odiv.getElementsByTagName("ul")[0];
  step+=(away-odiv.offsetLeft)/10;
  step=step*0.78;
 l=parseInt(odiv.offsetLeft+step);
 odiv.style.left=l+"px";
 oul.style.left=-l+432+"px";;
}
</script>
</head>
<body>
<div id="header">
 <ul>
 <li class="normal"><a href="#">首页</a></li>
 <li class="normal"><a href="#">叶子课程</a></li>
 <li class="normal"><a href="#">叶子资源</a></li>
 <li class="normal"><a href="#">留言</a></li>
 <li class="normal"><a href="#">叶子博客</a></li>
 <li class="normal"><a href="#">联系叶子</a></li>
 </ul>
 <div id="btn_bg">
  <ul>
  <li class="active"><a href="#">首页</a></li>
  <li class="active"><a href="#">叶子课程</a></li>
  <li class="active"><a href="#">叶子资源</a></li>
  <li class="active"><a href="#">留言</a></li>
  <li class="active"><a href="#">叶子博客</a></li>
  <li class="active"><a href="#">联系叶子</a></li>
  </ul>
 </div>
</div>
</body>
</html>