本文实例讲述了JS实现5秒钟自动封锁div层的方法。分享给大家供大家参考。具体实现方法如下：
<head>
<title>JS实现5秒钟自动封锁div层</title>
<style type="text/css">
<!--
#sponsorAdDiv {position:absolute; height:1; width:1; top:0; left:0;}
-->
</style>
</head>
<body>
<SCRIPT LANGUAGE="JavaScript1.2">
adTime=5; //封锁窗口期待的时间
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">
<table width="450" height="350" bgcolor="008000"><tr><td>
<table width="445" height="345" bgcolor="F0FFF0"><tr><td>
<center>welcome to www.CsrCode.cn!<BR><BR>这个窗口将在5秒后自动封锁</center>
</td></tr></table></td></tr></table></div>
</body>
</html>
希望本文所述对大家的javascript程序设计有所帮助。