代码简介：
代码内容：
<html>
<head>
<title>用JS+CSS写左侧可隐藏的展开、折叠菜单代码_网页代码站(www.webdm.cn)</title>
<script language="JavaScript1.2" type="text/javascript">
var maxmnus = 5
function opTab(){
var mnu = document.getElementById("menubar")
var arrdiv = document.getElementById("arrow")
var arrtxt = document.getElementById("arr")
if((mnu.style.display != "block") || (mnu.style.display == "")){
mnu.style.display = "block"
arrdiv.style.pixelLeft = mnu.style.width.substring(0 , mnu.style.width.length - 2)
arrtxt.innerText = "3";
} else {
mnu.style.display = "none"
arrtxt.innerText = "4";
arrdiv.style.pixelLeft = 0;
}
event.cancelBubble = true;
}
function toggleMenu(el){
for(var i = 0;i < maxmnus;i++) document.getElementById(document.getElementById("c" +
i).menu).style.display = "none";
if(el.status == "closed"){
el.status = "open"
document.getElementById(el.menu).style.display = "block";
} else {
el.status = "closed"
}
}
function toggleSub(e){
el = document.getElementById(e)
if(el.status == "closed"){
el.style.display = "block";
el.status = "open"
} else {
el.style.display = "none";
el.status = "closed"
}
event.cancelBubble = true;
}
</script>
<style type="text/css">
#menubar{
position:absolute;top:0px;left:0px;display:none;font-family:Verdana,Helvetica,Arial;font-
weight:700;font-size:12px;cursor:hand;z-index:5;background-image:url();background-repeat:repeat-
y;filter:progid:DXImageTransform.Microsoft.gradient
(enabled='true',gradientType='1',startColorstr='#2644b2', endColorstr='#e7e8f1');}
.indicator{
color:#b24426;font-family:Webdings;font-weight:bold;font-size:10px;}
.r1{
position:relative;top:10px;left:5px;213px;color:#e7e8f1;border-left:#e7e8f1 2px outset;border-
top:#e7e8f1 2px outset;border-right:#e7e8f1 2px outset;border-bottom:#e7e8f1 2px outset;/*
http://www.webdm.cn */padding-left:5px;padding-top:1px;adding-right:5px;padding-bottom:1px;background-
image:url();background-repeat:repeat-y;filter:progid:DXImageTransform.Microsoft.gradient
(enabled='true',gradientType='1',startColorstr='#2644b2', endColorstr='#e7e8f1');}
.submenu1{
position:relative;top:0px;left:0px;height:95%;100%;border-left:#e0f8e3 2px inset;border-
top:#e0f8e3 2px inset;border-right:#e0f8e3 2px inset;border-bottom:#e0f8e3 2px inset;padding-
left:3px;padding-top:3px;padding-right:3px;padding-bottom:3px;display:none;color:#2644b2;font-
family:Verdana,Helvetica,Arial;font-weight:700;font-size:12px;background-color:#cff1d4;background-
image:url();background-repeat:repeat-y;filter:progid:DXImageTransform.Microsoft.gradient
(enabled='true',gradientType='1',startColorstr='#bec1e4', endColorstr='#e7e8f1');}
.submenu2{
position:relative;top:0px;left:0px;90%;border-left:#e0f8e3 3px groove;border-top:#e0f8e3 3px
groove;border-right:#e0f8e3 3px groove;border-bottom:#e0f8e3 3px groove;padding-left:3px;padding-
top:3px;padding-right:3px;padding-bottom:3px;margin-top:4px;display:none;background-
color:#cff1d4;color:#2644b2;font-family:Verdana,Helvetica,Arial;font-weight:700;font-
size:10px;background-image:url();background-repeat:repeat-
y;filter:progid:DXImageTransform.Microsoft.gradient
(enabled='true',gradientType='1',startColorstr='#bec1e4', endColorstr='#e7e8f1');}
.pulltab{
position:absolute;top:0px;left:0px;height:100%;20px;padding-
left:2px;cursor:hand;color:#2644b2;font-family:Webdings;font-weight:bold;font-size:10px;z-
index:5;background-image:url();background-repeat:repeat-
y;filter:progid:DXImageTransform.Microsoft.gradient
(enabled='true',gradientType='1',startColorstr='#e7e8f1', endColorstr='#2644b2');}
.inner{
height:100%;100%;}
.mtab{
position:relative;top:0px;
.btninner{
height:100%;100%;}
.fr{
position:absolute;top:0px;left:30px;}
</style>
</head>
<body scroll="no">
<div id="menubar" style="; HEIGHT: expression(document.body.offsetHeight); WIDTH: 223px">
<div id="c0" class="r1" onclick="toggleMenu(this)" status="closed" menu="m0">
<div id="cbtn" class="btninner">代码下载</div>
<div class="mtab">
<table id="m0" class="submenu1" align="center" border="0" cellspacing="0" cellpadding="0">
<tr><td onclick="opTab();">论坛社区</td></tr>
<tr><td onclick="opTab();">交友会员</td></tr>
<tr><td onclick="opTab();">聊天留言</td></tr>
</table>
</div>
</div>
<div id="c1" class="r1" onclick="toggleMenu(this)" status="closed" menu="m1">
<div id="cbtn" class="btninner">产品及服务</div>
<div>
<table id="m1" class="submenu1" align="center" border="0" cellspacing="0" cellpadding="0">
<tr><td onclick="opTab();">新闻</td></tr>
<tr><td onclick="opTab();">产品</td></tr>
<tr><td onclick="opTab();">服务</td></tr>
</table>
</div>
</div>
<div id="c2" class="r1" onclick="toggleMenu(this)" status="closed" menu="m2">
<div id="cbtn" class="btninner">网页编程</div>
<div>
<table id="m2" class="submenu1" align="center" border="0" cellspacing="0" cellpadding="0">
<tr><td>XML</td></tr>
<tr><td>AJAX</td></tr>
<tr><td>JQUERY</td></tr>
</table>
</div>
</div>
<div id="c3" class="r1" onclick="toggleMenu(this)" status="closed" menu="m3">
<div id="cbtn" class="btninner">WEB开发</div>
<div>
<table id="m3" class="submenu1" align="center" border="0" cellspacing="0" cellpadding="0">
<tr><td>ASP</td></tr>
<tr><td>PHP</td></tr>
<tr><td>JSP</td></tr>
</table>
</div>
</div>
<div id="c4" class="r1" onclick="toggleMenu(this)" status="closed" menu="m4">
<div id="cbtn" class="btninner">演示</div>
<div>
<table id="m4" class="submenu1" align="center" border="0" cellspacing="0" cellpadding="0">
<tr><td>MENU 1</td></tr>
<tr><td>MENU 2</td></tr>
<tr><td>MENU 3</td></tr>
</table>
</div>
</div>
</div>
<div id="arrow" class="pulltab" onclick="opTab()"><table class="inner"><tr><td id="arr"
valign="middle">4</td></tr></table></div>
<div id="fr" name="fr" class="fr">
<h2>左侧的变化菜单</h2>
</div>
<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/09b322ca-6cdd-4ff5-bd30-ffbbbb278d79.html