你可以建立一个ads.js,下面就是这个JS文件的代码.把这个文件调用要你需要弹出广告的网页即可
function openpopup(){
document.writeln(" <SCRIPT language=JavaScript>");
document.writeln("window.open('http://siyizhu.126.com')");
document.writeln("</script\>");
}

function get_cookie(Name) {
var search = Name + "="
var returnvalue = "";
if (document.cookie.length > 0) {
offset = document.cookie.indexOf(search)
if (offset != -1) {
offset += search.length
end = document.cookie.indexOf(";", offset);
if (end == -1)
end = document.cookie.length;
returnvalue=unescape(document.cookie.substring(offset, end))
}
}
return returnvalue;
}

function helpor_net(){
if (get_cookie('popped')==''){
openpopup()
document.cookie="popped=yes"
}
}
helpor_net()
'http://siyizhu.126.com'部分换成你要弹出广告的URL.