本文實例講述了JS CSS實現大氣清新的滑動選單效果代碼。分享給大家參考，具體如下：
這是一款比較大氣清新的滑動導航選單，CSS和JavaScript配合完成，滑鼠放到一級選單上，會滑出二級的選單，相容性也不錯，適合大多數網站使用，用到兩張背景圖片，請拷貝圖片地址下載圖片。
運作效果截圖如下：
線上示範網址如下：
http://demo.jb51.net/js/2015/js-css-dqqx-scroll-menu-demo/
具體程式碼如下：
<!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>滑动导航菜单</title>
<style>
body {margin:25px; font:12px Verdana, Arial, Helvetica}
* {padding:0; margin:0}
.dropdown {float:left; padding-right:5px}
.dropdown dt {width:188px; border:2px solid #9ac1c9; padding:8px; font-weight:bold; cursor:pointer; background:url(images/header.gif)}
.dropdown dt:hover {background:url(images/header_over.gif)}
.dropdown dd {position:absolute; overflow:hidden; width:208px; display:none; background:#fff; z-index:200; opacity:0}
.dropdown ul {width:204px; border:2px solid #9ac1c9; list-style:none; border-top:none}
.dropdown li {display:inline}
.dropdown a, .dropdown a:active, .dropdown a:visited {display:block; padding:5px; color:#333; text-decoration:none; background:#eaf0f2; width:194px}
.dropdown a:hover {background:#d9e1e4; color:#000}
.dropdown .underline {border-bottom:1px solid #b9d6dc}
</style>
<script type="text/javascript">
var DDSPEED = 10;
var DDTIMER = 15;
function ddMenu(id,d){
var h = document.getElementById(id + '-ddheader');
var c = document.getElementById(id + '-ddcontent');
clearInterval(c.timer);
if(d == 1){
clearTimeout(h.timer);
if(c.maxh && c.maxh <= c.offsetHeight){return}
else if(!c.maxh){
c.style.display = 'block';
c.style.height = 'auto';
c.maxh = c.offsetHeight;
c.style.height = '0px';
}
c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
}else{
h.timer = setTimeout(function(){ddCollapse(c)},50);
}
}
function ddCollapse(c){
c.timer = setInterval(function(){ddSlide(c,-1)},DDTIMER);
}
function cancelHide(id){
var h = document.getElementById(id + '-ddheader');
var c = document.getElementById(id + '-ddcontent');
clearTimeout(h.timer);
clearInterval(c.timer);
if(c.offsetHeight < c.maxh){
c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
}
}
function ddSlide(c,d){
var currh = c.offsetHeight;
var dist;
if(d == 1){
dist = (Math.round((c.maxh - currh) / DDSPEED));
}else{
dist = (Math.round(currh / DDSPEED));
}
if(dist <= 1 && d == 1){
dist = 1;
}
c.style.height = currh + (dist * d) + 'px';
c.style.opacity = currh / c.maxh;
c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
if((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1)){
clearInterval(c.timer);
}
}
</script>
</head>
<body>
<dl class="dropdown">
<dt id="one-ddheader" onmouseover="ddMenu('one',1)" onmouseout="ddMenu('one',-1)">源码下载</dt>
<dd id="one-ddcontent" onmouseover="cancelHide('one')" onmouseout="ddMenu('one',-1)">
<ul>
<li><a href="#" class="underline">最新源码</a></li>
<li><a href="#" class="underline">下载排行</a></li>
<li><a href="#" class="underline">脚本资源</a></li>
<li><a href="#">Ajax实例</a></li>
</ul>
</dd>
</dl>
<dl class="dropdown">
<dt id="two-ddheader" onmouseover="ddMenu('two',1)" onmouseout="ddMenu('two',-1)">网页特效</dt>
<dd id="two-ddcontent" onmouseover="cancelHide('two')" onmouseout="ddMenu('two',-1)">
<ul>
<li><a href="#" class="underline">菜单导航</a></li>
<li><a href="#" class="underline">层和布局</a></li>
<li><a href="#" class="underline">图片特效</a></li>
</ul>
</dd>
</dl>
</body>
</html>
希望本文所述對大家JavaScript程式設計有所幫助。
