开启页面一段时间自动关闭广告的代码

开启页面一段时间自动关闭广告的代码:

<SCRIPT LANGUAGE="JavaScript1.2">
adTime=5; //关闭窗口等待的时间

chanceAd=1;
var ns=(document.layers);
var ie=(document.all);
var w3=(document.getElementById && !ie);
adCount=0;
function initAd(){
if(!ns && !ie && !w3) return;
if(ie) adDiv=eval('document.all.sponsorAdDiv.style');
else if(ns) adDiv=eval('document.layers["sponsorAdDiv"]');
else if(w3) adDiv=eval('document.getElementById("sponsorAdDiv").style');
randAd=Math.ceil(Math.random()*chanceAd);
if (ie||w3)
adDiv.visibility="visible";
else
adDiv.visibility ="show";
if(randAd==1) showAd();
}
function showAd(){
if(adCount<adTime*10){adCount+=1;
if (ie){documentWidth =document.body.offsetWidth/2+document.body.scrollLeft-20;
documentHeight =document.body.offsetHeight/2+document.body.scrollTop-20;}
else if (ns){documentWidth=window.innerWidth/2+window.pageXOffset-20;
documentHeight=window.innerHeight/2+window.pageYOffset-20;}
else if (w3){documentWidth=self.innerWidth/2+window.pageXOffset-20;
documentHeight=self.innerHeight/2+window.pageYOffset-20;}
adDiv.left=documentWidth-200;adDiv.top =documentHeight-200;
setTimeout("showAd()",100);}else closeAd();
}
function closeAd(){
if (ie||w3)
adDiv.display="none";
else
adDiv.visibility ="hide";
}
onload=initAd;
</script>
<div id="sponsorAdDiv" style="visibility:hidden" align="center">

<!--广告内容，可以是图片或FLASH-->
<img src="http://www.szlg.net/UploadFiles/2011-02/admin/2011.png" />
</div>

如果是FLASH，将上面图片换成FLASH的代码即可。