var ads_time = 500;
var ads_h = 0;
function addCount()
{
if(ads_time>0)
{
ads_time--;
ads_h = ads_h+50;
}
else
{
return;
}
if(ads_h>=300) //高度
{
return;
}
document.getElementById("ads").style.display = "";
document.getElementById("ads").style.height = ads_h+"px";
setTimeout("addCount()",10); 
}

window.onload = function showAds()
{
addCount();
setTimeout("noneAds()",8000); //停留时间自己适当调整
}

var ads_T = 250;
var ads_N = 250; //高度。如果高度调整不正确，可能会导致图片无法自动收缩
function noneAds()
{
if(ads_T>0)
{
ads_T--;
ads_N = ads_N-25;
}
else
{
return;
}
if(ads_N<=0)
{
document.getElementById("ads").style.display = "none";
return;
}

document.getElementById("ads").style.height = ads_N+"px";
setTimeout("noneAds()",10); 
}