网页动态广告制作代码是什么啊？？？谢谢啊！

把下面这段代码保存为 adver-left.js
var imgheight
var imgleft
document.ns = navigator.appName == "Netscape"
window.screen.width>800 ? imgheight=100:imgheight=100
window.screen.width>800 ? imgleft=15:imgleft=122
function myload()
{
if (navigator.appName == "Netscape")
{document.myleft.pageY=pageYOffset+window.innerHeight-imgheight;
document.myleft.pageX=imgleft;
leftmove();
}
else
{
myleft.style.top=document.body.scrollTop+document.body.offsetHeight-imgheight;
myleft.style.left=imgleft;
leftmove();
}
}
function leftmove()
{
if(document.ns)
{
document.myleft.top=pageYOffset+window.innerHeight-imgheight
document.myleft.left=imgleft;
setTimeout("leftmove();",80)
}
else
{
myleft.style.top=document.body.scrollTop+document.body.offsetHeight-imgheight;
myleft.style.left=imgleft;