JS+CSS打造三级折叠菜单，自动收缩其它级 js

<html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" />

<title>JS+CSS打造三级折叠菜单，自动收缩其它级</title>

<style>

*,body,ul,h1,h2{ margin:0; padding:0; list-style:none;}

body{font:12px "宋体"; padding-top:20px;} a{ color:white;border:none;}

#menu { width:200px; margin:auto;}

#menu h1 { font-size:12px; border:gray 1px solid; margin-top:1px;  background-color:gray;}

#menu h2 { font-size:12px; border:#E7E7E7 1px solid; border-top-color:#FFF; background-color:#00CCFF;}

#menu ul { padding-left:0px; height:auto;border:#E7E7E7 1px solid; border-top:none;overflow:auto;}

#menu a { display:block; padding:5px 0 3px 10px; text-decoration:none; overflow:hidden;}

#menu ul a { display:block; padding:5px 0 3px 15px; text-decoration:none; overflow:hidden;background-color:white;color:black;}

#menu ul a:hover  {      color:Black;background:red;      }

#menu a:hover{ color:white; background:red;}  #menu .no {display:none;}

</style>

<script language="JavaScript">

function ShowMenu(obj, n) {

var Nav = obj.parentNode;

if (!Nav.id) {

var BName = Nav.getElementsByTagName("ul");

var HName = Nav.getElementsByTagName("h2");

var t = 2;

} else {

var BName = document.getElementById(Nav.id).getElementsByTagName("span");

var HName = document.getElementById(Nav.id).getElementsByTagName("h1");

var t = 1;

}

for (var i = 0; i < HName.length; i++) {

HName[i].innerHTML = HName[i].innerHTML.replace("-", "+");

HName[i].className = "";

}

obj.className = "h" + t;

for (var i = 0; i < BName.length; i++)

{ if (i != n) { BName[i].className = "no"; } }

if (BName[n].className == "no") {

BName[n].className = "";

obj.innerHTML = obj.innerHTML.replace("+", "-");

} else {

BName[n].className = "no";

obj.className = "";

obj.innerHTML = obj.innerHTML.replace("-", "+");

}

}

</script>

</head>

<body>

<div id="menu">

<h1 onclick="javascript:ShowMenu(this,0)"><a href="javascript:void(0)">+ 一级菜单A</a></h1>

<span class="no">

<h2 onclick="javascript:ShowMenu(this,0)"><a href="javascript:void(0)">+ 一级菜单A_1</a></h2>

<ul class="no">

<a href="javascript:void(0)">一级菜单A_0</a>

<a href="javascript:void(0)">一级菜单A_1</a>

<a href="javascript:void(0)">一级菜单A_2</a>

<a href="javascript:void(0)">一级菜单A_3</a>

</ul>

<h2 onclick="javascript:ShowMenu(this,1)"><a href="javascript:void(0)">+ 一级菜单A_2</a></h2>

<ul class="no">    <a href="javascript:void(0)">一级菜单A_0</a>

<a href="javascript:void(0)">一级菜单A_1</a>

<a href="javascript:void(0)">一级菜单A_2</a>

<a href="javascript:void(0)">一级菜单A_3</a>

</ul>  </span>

<h1 onclick="javascript:ShowMenu(this,1)"><a href="javascript:void(0)">+ 二级菜单B</a></h1>

<span class="no">

<h2 onclick="javascript:ShowMenu(this,0)"><a href="javascript:void(0)">+ 二级菜单B_1</a></h2>

<ul class="no">

<a href="javascript:void(0)">二级菜单B_0</a>

<a href="javascript:void(0)">二级菜单B_1</a>

<a href="javascript:void(0)">二级菜单B_2</a>

<a href="javascript:void(0)">二级菜单B_3</a>

</ul>

<h2 onclick="javascript:ShowMenu(this,1)">

<a href="javascript:void(0)">+ 二级菜单B_2</a></h2>

<ul class="no">    <a href="javascript:void(0)">二级菜单B_0</a>

<a href="javascript:void(0)">二级菜单B_1</a>

<a href="javascript:void(0)">二级菜单B_2</a>

</ul>  </span>

<h1 onclick="javascript:ShowMenu(this,2)">

<a href="javascript:void(0)">+ 三级菜单C</a></h1>

<span class="no">   <h2 onclick="javascript:ShowMenu(this,0)">

<a href="javascript:void(0)">+ 三级菜单C_1</a></h2>

<ul class="no">    <a href="javascript:void(0)">三级菜单C_0</a>

<a href="javascript:void(0)">三级菜单C_1</a>

<a href="javascript:void(0)">三级菜单C_2</a>   </ul>

<h2 onclick="javascript:ShowMenu(this,1)">

<a href="javascript:void(0)">+ 三级菜单C_2</a></h2>

<ul class="no">    <a href="javascript:void(0)">三级菜单C_0</a>

<a href="javascript:void(0)">三级菜单C_1</a>   </ul>  </span>

<h1 onclick="javascript:ShowMenu(this,3)">

<a href="javascript:void(0)">+ 四级菜单D</a></h1>  <span class="no">

<h2 onclick="javascript:ShowMenu(this,0)">

<a href="javascript:void(0)">+ 四级菜单D_1</a></h2>   <ul class="no">

<a href="javascript:void(0)">四级菜单D_0</a>

<a href="javascript:void(0)">四级菜单D_1</a>   </ul>

<h2 onclick="javascript:ShowMenu(this,1)">

<a href="javascript:void(0)">+ 四级菜单D_2</a></h2>   <ul class="no">

<a href="javascript:void(0)">四级菜单D_0</a>

<a href="javascript:void(0)">四级菜单D_1</a>

<a href="javascript:void(0)">四级菜单D_2</a>

<a href="javascript:void(0)">四级菜单D_3</a>

</ul>

</span>

</div>

</body>

</html>