例子，js下拉菜单，小巧实用。效果如图：
<!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" />
<title>js下拉菜单代码-www.jb200.com</title>
<style>
#sddm
{margin: 0 auto;
padding: 0;
z-index: 30;
background-color:#F4F4F4;
width: 480px;
height:23px;}
#sddm li
{margin: 0;
padding: 0;
list-style: none;
float: left;
font: bold 12px arial}
#sddm li a
{display: block;
margin: 0 1px 0 0;
padding: 4px 10px;
width: 60px;
background: #5970B2;
color: #FFF;
text-align: center;
text-decoration: none}
#sddm li a:hover
{background: #49A3FF}
#sddm div
{position: absolute;
visibility: hidden;
margin: 0;
padding: 0;
background: #EAEBD8;
border: 1px solid #5970B2}
#sddm div a
{position: relative;
display: block;
margin: 0;
padding: 5px 10px;
width: auto;
white-space: nowrap;
text-align: left;
text-decoration: none;
background: #EAEBD8;
color: #2875DE;
font: 12px arial}
#sddm div a:hover
{
background: #49A3FF;
color: #FFF；
}
</style>
<!-- dd menu -->
<script type="text/javascript">
<!--
var timeout = 500;
var closetimer= 0;
var ddmenuitem = 0;
// open hidden layer
function mopen(id)
{
// cancel close timer
mcancelclosetime();
// close old layer
if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';
// get new layer and show it
ddmenuitem = document.getElementById(id);
ddmenuitem.style.visibility = 'visible';
}
// close showed layer
function mclose()
{
if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';
}
// go close timer
function mclosetime()
{
closetimer = window.setTimeout(mclose, timeout);
}
// cancel close timer
function mcancelclosetime()
{
if(closetimer)
{
window.clearTimeout(closetimer);
closetimer = null;
} // www.jb200.com
}
// close layer when click-out
document.onclick = mclose;
// -->
</script>
</head>
<body style="text-align:center">
<ul id="sddm">
<li><a href="#" onmouseover="mopen('m1')" onmouseout="mclosetime()">主页</a>
<div id="m1" onmouseover="mcancelclosetime()" onmouseout="mclosetime()">
<a href="#">最新更新</a>
<a href="#">热点排行</a>
<a href="#">推荐阅读</a>
</div>
</li>
<li><a href="#" onmouseover="mopen('m2')" onmouseout="mclosetime()">下载频道</a>
<div id="m2" onmouseover="mcancelclosetime()" onmouseout="mclosetime()">
<a href="#">ASP源程序</a>
<a href="#">AJAX菜单</a>
<a href="#">DIV布局实例</a>
</div>
</li>
<li><a href="#" onmouseover="mopen('m3')" onmouseout="mclosetime()">文章资讯</a>
<div id="m3" onmouseover="mcancelclosetime()" onmouseout="mclosetime()">
<a href="#">Visa相关</a>
<a href="#">Paypal相关</a>
</div>
</li>
<li><a href="#" onmouseover="mopen('m4')" onmouseout="mclosetime()">帮助中心</a>
<div id="m4" onmouseover="mcancelclosetime()" onmouseout="mclosetime()">
<a href="#">下载帮助文档</a>
<a href="#">在线阅读</a>
</div>
</li>
<li><a href="#" onmouseover="mopen('m5')" onmouseout="mclosetime()">联系博主</a>
<div id="m5" onmouseover="mcancelclosetime()" onmouseout="mclosetime()">
<a href="#">E-mail</a>
<a href="#">在线提交</a>
<a href="http://www.yuju100.com/" target="_blank">语句百分网</a>
</div>
</li>
</ul>
<div style="clear:both"></div>
<p>小巧实用的js下拉菜单代码，兼容：ie6+, firefox 1.5+, opera 8+, safari 3+, chrome 0.2+</p>
</body>
</html>