日期:2014-05-16  浏览次数:20337 次

为什么js没用??哪里错了?
JScript code
<!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=gb2312" />

<style type="text/css">
   #a_div { line-height:25px;font-weight:600;color:blue;}
   #a_div ul { display:none;text-decoration:none;margin:0px;}
   #a_div .ch_div { color:red;}
   #a_div ul.ch_ul { display:block;}
</style>

<script type="text/javascript">
start=function()
 {
   var a=document.getElementById("a_div");
   var b=a.getElementsByTagName("ul");

   a.onmouseover=function(){ this.className="ch_div";b.className="ch_ul";}
   a.onmouseout=function(){ this.className="";b.className="";}  
 }
window.onload=start;
</script>

</head>
<body>

<div id="a_div" >导航
<ul>
<li>内容1</li>
<li>内容2</li>
</ul>
</div>

</body>
</html>



------解决方案--------------------
b[0]. className
------解决方案--------------------
JScript code
// var b = a.getElementsByTagName("ul");
   var b = a.getElementsByTagName("ul")[0];