本文實例講述了JS CSS相對定位實現的下拉式選單。分享給大家供大家參考。具體如下：
這裡使用的是相對定位，不過效果還可以，用時候再修整一下，這個只是實現了大概功能，還有許多細節沒有修飾。
運作效果截圖如下：
線上示範網址如下：
http://demo.jb51.net/js/2015/js-css-ab-fix-menu-codes/
具體程式碼如下：
<html>
<head>
<title>非定位CSS+Js下拉菜单</title>
<style>
#menu {
position: absolute;
font-family: sans-serif;
font-size: 9pt;
}
#menu li {
float: left;
list-style-type: none;
width: 102px;
background-color: skyblue;
border: 1px solid #0066cc;
text-indent: 0px;
margin-left: 3px;
}
#menu li a {
color: blue;
text-decoration: none;
width: 100%;
display: block;
}
#menu li a:hover {
color: white;
}
#menu li ul {
background-color: skyblue;
margin: 0px;
padding: 0px;
}
#menu li ul li {
padding: 0px;
margin: 0px;
float: none;
list-style-type: none;
width: 100px;
text-indent: 0px;
border: none;
}
#menu li ul li a{
color: black;
text-decoration: none;
}
#menu li ul li a:hover{
color: black;
background-color: aqua;
}</style>
<script language="javascript" type="text/javascript">
var t=false,current;
function SetupMenu() {
if (!document.getElementsByTagName) return;
items=document.getElementsByTagName("li");
for (i=0; i<items.length; i++) {
if (items[i].className != "menu") continue;
thelink=findChild(items[i],"A");
thelink.onmouseover=ShowMenu;
thelink.onmouseout=StartTimer;
if (ul=findChild(items[i],"UL")) {
ul.style.display="none";
for (j=0; j<ul.childNodes.length; j++) {
ul.childNodes[j].onmouseover=ResetTimer;
ul.childNodes[j].onmouseout=StartTimer;
}
}
}
}
function findChild(obj,tag) {
cn = obj.childNodes;
for (k=0; k<cn.length; k++) {
if (cn[k].nodeName==tag) return cn[k];
}
return false;
}
function ShowMenu(e) {
if (!e) var e = window.event;
thislink = (e.target) ? e.target: e.srcElement;
ResetTimer();
if (current) HideMenu(current);
thislink = thislink.parentNode;
current=thislink;
ul = findChild(thislink,"UL");
if (!ul) return;
ul.style.display="block";
}
function HideMenu(thelink) {
ul = findChild(thelink,"UL");
if (!ul) return;
ul.style.display="none";
}
function ResetTimer() {
if (t) window.clearTimeout(t);
}
function StartTimer() {
t = window.setTimeout("HideMenu(current)",200);
}
window.onload=SetupMenu;
</script>
</head>
<body>
<h1>Menu Test</h1>
<ul id="menu">
<li class="menu"><a href="#">Home</a></li>
<li class="menu"><a href="#">Products</a>
<ul>
<li><a href="#">Sub-item 1</a></li>
<li><a href="#">Sub-item 2</a></li>
</ul>
</li>
<li class="menu"><a href="#">Support</a>
<ul>
<li><a href="#">Sub-item 1</a></li>
<li><a href="#">Sub-item 2</a></li>
</ul>
</li>
<li class="menu"><a href="#">Employment</a>
<ul>
<li><a href="#">Sub-item 1</a></li>
<li><a href="#">Sub-item 2</a></li>
</ul>
</li>
<li class="menu"><a href="#">Contact Us</a>
<ul>
<li><a href="#">Sub-item 1</a></li>
<li><a href="#">Sub-item 2</a></li>
</ul>
</li>
</ul>
</body>
</html>
希望本文所述對大家的JavaScript程式設計有所幫助。
