点击向下展开的下拉菜单特效

点击向下展开的下拉菜单特效代码，无调用jQuery，真正的JS下拉菜单，兼容性方面未做测试，觉得有用处的自己测试修正吧，本文仅提供基础的代码供参考。

 1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 2 <html xmlns="http://www.w3.org/1999/xhtml">
 3 <head>
 4 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 5 <title>下拉菜单</title>
 6 <style type="text/css">
 7 *{margin:0; padding:0}
 8 #nav{width:200px; margin:50px}
 9 #nav h3{ cursor:pointer; line-height:30px; height:30px; background-color:#000000; color:#fff}
10 #nav a{display:block; line-height:24px;color:#666666}
11 #nav a:hover{background-color:#eee; color:#000;}
12 #nav div{display:none; border:1px solid #000; border-top:none}
13 </style>
14 <script type="text/javascript">
15 function $(id){return document.getElementById(id)}
16 window.onload = function(){
17  $("nav").onclick = function(e){
18   var src = e?e.target:event.srcElement;
19   if(src.tagName == "H3"){
20    var next = src.nextElementSibling || src.nextSibling;
21    next.style.display = (next.style.display =="block")?"none":"block";
22   }
23  }
24 }
25 </script>
26 </head>
27 
28 <body>
29 <div id="nav">
30  <h3>管理区</h3>
31     <div>
32      <a href="#">建议</a>
33         <a href="#">链接</a>
34         <a href="#">联系</a>
35     </div>
36     <h3>交流区</h3>
37     <div>
38      <a href="#">JavaScript</a>
39         <a href="#">Delphi</a>
40         <a href="#">VC++</a>
41     </div>
42 </div>
43 </body>
44 </html>