<style type="text/css">
#main{text-align:center;}
#adver{
position:absolute;
left:50px;
top:30px;
z-index:2;
}
</style>
<script src="js/scroll.js"></script>
</head>
<body>
<div id="adver"><img src="images/adv.jpg"/></div>
<div id="main"><img src="images/main1.jpg"/><img src="images/main2.jpg"/><img src="images/main3.jpg"/></div>
</body>
var adverTop; //层距页面顶端距离
var adverLeft;
var adverObject; //层对象
function inix(){
adverObject=document.getElementById("adver"); //获得层对象
if(adverObject.currentStyle){
adverTop=parseInt(adverObject.currentStyle.top);
adverLeft=parseInt(adverObject.currentStyle.left);
}
else{
adverTop=parseInt(document.defaultView.getComputedStyle(adverObject,null).top);
adverLeft=parseInt(document.defaultView.getComputedStyle(adverObject,null).left);
}
}
function move(){
adverObject.style.top=adverTop+parseInt(document.documentElement.scrollTop)+"px";
adverObject.style.left=adverLeft+parseInt(document.documentElement.scrollLeft)+"px";
}
window.onload=inix;
window.onscroll=move;