慢慢展开再慢慢收起的javascript广告效果

<!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>脚本之家 效果代码</title> 
<style> 
*{margin:0;padding:0;} 
body {height:2000px;} 
#menu { 
    width:220px; 
    height:420px; 
    position:absolute; 
    z-index:1000; 
    background:url(/upload/20080421090108362.gif) repeat-x top left; 
} 
#menu_h { 
    float:right; 
} 
#menu_h img { 
    cursor:pointer; 
} 
#menu_c { 
    width:188px; 
    height:398px; 
    border:1px solid #666; 
    background:#ecf6f5; 
    margin:12px 0 0 5px; 
} 
#menu_c h2 { 
    text-align:center; 
} 
</style> 
</head> 
<body> 
<div id="ads" style="width:900px;height:300px;background:#369;margin:0 auto;"></div> 
<script type="text/javascript"> 
var time = 300; 
var h = 0; 
function addCount() 
{ 
    if(time>0) 
    { 
        time--; 
        h = h+5; 
    } 
    else 
    { 
        return; 
    } 
    if(h>300)  //高度 
    { 
        return; 
    } 
    document.getElementById("ads").style.display = ""; 
    document.getElementById("ads").style.height = h+"px"; 
    setTimeout("addCount()",30); 
} 
window.onload = function showAds() 
{ 
    addCount(); 
    setTimeout("noneAds()",7000); //停留时间自己调了 
} 
var T = 300; 
var N = 300; //高度 
function noneAds() 
{ 
    if(T>0) 
    { 
        T--; 
        N = N-5; 
    } 
    else 
    { 
        return; 
    } 
    if(N<0) 
    { 
        document.getElementById("ads").style.display = "none"; 
        return; 
    } 
    document.getElementById("ads").style.height = N+"px"; 
    setTimeout("noneAds()",30); 
} 
</ script> 
</body> 
</html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]

慢慢展开再慢慢收起的javascript广告效果_广告代码