注意是用到了，下列的演示
<scriptlanguage="JavaScript"type="text/javascript">
adTime=8;
chanceAd=1;
varns=(document.layers);
varie=(document.all);
varw3=(document.getElementById&&!ie);
adCount=0;
functioninitAd(){
if(!ns&&!ie&&!w3)return;
if(ie)adDiv=eval('document.all.sponsorAdDiv.style');
elseif(ns)adDiv=eval('document.layers["sponsorAdDiv"]');
elseif(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();
}
functionshowAd(){
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;}
elseif(ns){documentWidth=window.innerWidth/2+window.pageXOffset-20;
documentHeight=window.innerHeight/2+window.pageYOffset-20;}
elseif(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);}
}
functioncloseAd(){
if(ie||w3)
adDiv.display="none";
else
adDiv.visibility="hide";
}
function$(obj){
returndocument.getElementById(obj);
}

functioncheckForm(){
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");
returnfalse;
}
else
{
returntrue;
}
}
else
{
alert("您还没有选中需要上传的图片");
returnfalse;
}
}
文件打包下载