本文实例讲述了JavaScript实现横向滑出的多级菜单效果。分享给大家供大家参考。具体如下：
这是一款JavaScript横向滑出的多级菜单，只用鼠标放上就可以动画出现二级菜单，整体设计精美，大气，博客上也可以用哦。
运行效果截图如下：
在线演示地址如下：
http://demo.jb51.net/js/2015/js-hx-show-menu-style-demo/
具体代码如下：
<!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>JavaScript横向滑出的多级菜单</title>
<style>
* {padding:0; margin:0}
body {font:12px Verdana, Arial, Helvetica}
#wrapper {width:750px; padding:25px; margin:0 auto}
#leftcolumn {float:left; width:225px}
#rightcolumn {float:left; width:525px}
.dropdown {display:block; position:relative}
.dropdown dt {width:188px; border:2px solid #9ac1c9; padding:8px; font-weight:bold; cursor:pointer; background:url(images/header.gif)}
.dropdown .upperdd {border-bottom:none}
.dropdown dt:hover {background:url(images/header_over.gif)}
.dropdown dd {position:absolute; top:0; overflow:hidden; width:208px; display:none; background:#fff; opacity:0}
.dropdown ul {width:204px; border:2px solid #9ac1c9; list-style: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;
var OFFSET = -2;
var ZINT = 100;
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);
c.style.display = 'block';
if(c.maxh && c.maxh <= c.offsetHeight){return}
else if(!c.maxh){
c.style.left = (h.offsetWidth + OFFSET) + 'px';
c.style.height = 'auto';
c.maxh = c.offsetHeight;
c.style.height = '0px';
}
ZINT = ZINT + 1;
c.style.zIndex = ZINT;
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 > (c.maxh - 2) && d == 1){
clearInterval(c.timer);
}else if(dist < 1 && d != 1){
clearInterval(c.timer);
c.style.display = 'none';
}
}
</script>
</head>
<body>
<div id="wrapper">
<div id="leftcolumn">
<dl class="dropdown">
<dt id="one-ddheader" class="upperdd" onmouseover="ddMenu('one',1)" onmouseout="ddMenu('one',-1)">我们首页</dt>
<dd id="one-ddcontent" onmouseover="cancelHide('one')" onmouseout="ddMenu('one',-1)">
<ul>
<li><a href="#" class="underline">脚本主页</a></li>
<li><a href="#" class="underline">网页特效</a></li>
<li><a href="#">脚本下载</a></li>
</ul>
</dd>
</dl>
<dl class="dropdown">
<dt id="two-ddheader" class="upperdd" onmouseover="ddMenu('two',1)" onmouseout="ddMenu('two',-1)">网站导航</dt>
<dd id="two-ddcontent" onmouseover="cancelHide('two')" onmouseout="ddMenu('two',-1)">
<ul>
<li><a href="#" class="underline">ASP</a></li>
<li><a href="#" class="underline">PHP</a></li>
<li><a href="#" class="underline">.NET</a></li>
<li><a href="#">网站留言</a></li>
</ul>
</dd>
</dl>
<dl class="dropdown">
<dt id="three-ddheader" class="upperdd">最新下载</dt>
</dl>
<dl class="dropdown">
<dt id="four-ddheader" onmouseover="ddMenu('four',1)" onmouseout="ddMenu('four',-1)">欢迎回来</dt>
<dd id="four-ddcontent" onmouseover="cancelHide('four')" onmouseout="ddMenu('four',-1)">
<ul>
<li><a href="#" class="underline">欢迎再来</a></li>
<li><a href="#">慢走，不送</a></li>
</ul>
</dd>
</dl>
</div>
</div>
</body>
</html>
希望本文所述对大家的JavaScript程序设计有所帮助。
