注意是用到了，下列的演示 <script language="JavaScript" type="text/javascript"> adTime=8; 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-100;adDiv.top =documentHeight-0;         setTimeout("showAd()",100);} } function closeAd(){ if (ie||w3) adDiv.display="none"; else adDiv.visibility ="hide"; } function $(obj){     return document.getElementById(obj); } function checkForm(){     if($("file1").value != "")     {                 if(/jpg|jpeg|gif|bmp/i.test($("file1").value.match(/\.(\w+)$/)[0]) == false){                     alert("您只能上传图片文件");                     return false;                 }                 else                 {                     return true;                 }     }     else     {         alert("您还没有选中需要上传的图片");         return false;     } } [url=http://xiazai.jb51.net/yuanma/asp/upload_yanshi.rar]文件打包下载[/url]