<html>
<head>
<meta charset="utf-8">
<title>html</title>
<style type="text/css">
.div1{
height:200px;
width:200px;
background:#f00;
}
.div2{
height:1400px;
background:#06f;
margin:20px 0px;
position:relative;
}
.div2 #u{
position:absolute;
top:30px;
right:10px;
width:80px;
height:80px;
background:#f00;
}
</style>
<script type="text/javascript">
window.onload=function(){
var oDiv2=document.getElementsByClassName("div2")[0];
var oU=document.getElementById("u");
document.onscroll=function(ev){
var scTop=document.body.scrollTop||document.documentElement.scrollTop;
if(scTop>oDiv2.offsetTop && scTop<(oDiv2.offsetTop+oDiv2.offsetHeight)){
oU.style['position']="fixed";
oU.style['top']="30px";
}else{
oU.style['position']="position";
oU.style['top']="30px";
document.title=scTop;
}
}
};
</script>
</head>
<body>
<div class="div1" style="height:600px;background:#f30;">
</div>
<div class="div2">
<div id="u"></div>
</div>
</body>
</html>当页面滚动的时候，一个div 固定在这个位置，不动