JavaScript 下拉菜单实现代码

<!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 runat="server"> 
<title>JavaScript下拉菜单</title> 
<style type="text/css"> 
* { 
padding:0; 
margin:0; 
} 
body { 
font-family:verdana, sans-serif; 
font-size:small; 
} 
#navigation, #navigation li ul { 
list-style-type:none; 
} 
#navigation { 
margin:20px; 
} 
#navigation li { 
float:left; 
text-align:center; 
position:relative; 
} 
#navigation li a:link, #navigation li a:visited { 
display:block; 
text-decoration:none; 
color:#000; 
width:120px; 
height:40px; 
line-height:40px; 
border:1px solid #fff; 
border-width:1px 1px 0 0; 
background:#c5dbf2; 
padding-left:10px; 
} 
#navigation li a:hover { 
color:#fff; 
background:#2687eb; 
} 
#navigation li ul li a:hover { 
color:#fff; 
background:#6b839c; 
} 
#navigation li ul { 
display:none; 
position:absolute; 
top:40px; 
left:0; 
margin-top:1px; 
width:120px; 
} 
#navigation li ul li ul { 
display:none; 
position:absolute; 
top:0px; 
left:130px; 
margin-top:0; 
margin-left:1px; 
width:120px; 
} 
</style> 
<script type="text/javascript"> 
function displaySubMenu(li) { 
var subMenu = li.getElementsByTagName("ul")[0]; 
subMenu.style.display = "block"; 
} 
function hideSubMenu(li) { 
var subMenu = li.getElementsByTagName("ul")[0]; 
subMenu.style.display = "none"; 
} 
</script> 
</head> 
<body> 
<ul id="navigation"> 
<li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)"> 
栏目1 
<ul> 
<li>栏目1->菜单1</li> 
<li>栏目1->菜单2</li> 
<li>栏目1->菜单3</li> 
<li>栏目1->菜单4</li> 
</ul> 
</li> 
<li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)"> 
栏目2 
<ul> 
<li>栏目2->菜单1</li> 
<li>栏目2->菜单2</li> 
<li>栏目2->菜单3</li> 
<li>栏目2->菜单4</li> 
<li>栏目2->菜单5</li> 
</ul> 
</li> 
<li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)"> 
栏目3 
<ul> 
<li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)"> 
栏目3->菜单1 
<ul> 
<li>菜单1->子菜单1</li> 
<li>菜单1->子菜单2</li> 
<li>菜单1->子菜单3</li> 
<li>菜单1->子菜单4</li> 
</ul> 
</li> 
<li>栏目3->菜单2</li> 
<li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)"> 
栏目3->菜单3 
<ul> 
<li>菜单3->子菜单1</li> 
<li>菜单3->子菜单2</li> 
<li>菜单3->子菜单3</li> 
</ul> 
</li> 
</ul> 
</li> 
</ul> 
</body> 
</html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]