代码简介：
js实现无限级树形下拉导航菜单，简洁实用，用到一个已封装好的JS类，有用的大家借鉴一下。
代码内容：
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>js实现无限级树形导航列表_网页代码站(www.webdm.cn)</title>
</head>
<body>
<style type="text/css">
*{ margin:0; padding:0; list-style:none;}
body { margin:20px;}
h2 { font-family:"黑体"; font-size:24px; text-align:center; line-height:32px;}
h5 { font-size:12px; text-align:center; font-weight:normal; color:#666; line-height:28px;}
#nav a { text-decoration:underline;color:#06c; font-size:14px; line-height:24px;}
#nav ul{ margin-bottom:5px;}
#nav strong{ color:#696;}
#nav.dyn li ul{ display:none;}
#nav.dyn li ul.show{ display:block;}
#nav.dyn li{ padding-left:15px;}
#nav.dyn li.parent{ background:url(http://www.webdm.cn/images/20100422/user_23.gif) 5px 10px no-repeat;}
#nav.dyn li.open{ background:url(http://www.webdm.cn/images/20100422/user_23.gif) 5px -34px no-repeat;}
</style>
<script type="text/javascript">
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DOMhelp.debug.innerHTML+=bug+'\n';
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DOMhelp.addEvent(window, 'load', DOMhelp.init, false);
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DOMhelp.addEvent(window,'load',sn.init,false);
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</script>
<h2>js实现无限级树形导航列表</h2>
<ul id="nav">
<li><a href="#">主页</a></li>
<li><a href="#">产品</a>
<ul>
<li><a href="#">大类别一</a>
<ul>
<li><a href="#">小类别一</a>
<ul>
<li><a href="#">次类别一</a></li>
<li><a href="#">次类别二</a></li>
</ul>
</li>
<li><a href="#">小类别二</a></li>
</ul>
</li>
<li><a href="#">大类别二</a></li>
<li><a href="#">大类别三</a>
<ul>
<li><a href="#">小类别一</a></li>
<li><a href="#">小类别二</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#">服务</a>
<ul>
<li><a href="#">大类别一</a></li>
<li><a href="#">大类别二</a></li>
<li><a href="#">大类别三</a></li>
</ul>
</li>
<li><a href="#">合作</a></li>
<li><a href="#">关于我们</a>
<ul>
<li><a href="#">大类别一</a>
<ul>
<li><a href="#">小类别一</a></li>
<li><a href="#">小类别二</a></li>
</ul>
</li>
<li><a href="#">大类别二</a>
<ul>
<li><a href="#">小类别一</a></li>
<li><a href="#">小类别二</a></li>
</ul>
</li>
<li><a href="#">大类别三</a>
<ul>
<li><a href="#">小类别一</a></li>
<li><a href="#">小类别二</a></li>
</ul>
</li>
<li><a href="#">大类别四</a></li>
</ul>
</li>
<li><a href="#">联系我们</a>
<ul>
<li><a href="#">大类别一</a></li>
<li><a href="#">大类别二</a></li>
</ul>
</li>
</ul>
</body>
</html>
<br>
<p><a href="http://www.webdm.cn">网页代码站</a> - 最专业的代码下载网站 - 致力为中国站长提供有质量的代码！</p>
代码来自：http://www.webdm.cn/webcode/48291327-5795-4e03-a07f-8e167900afcf.html