<!DOCTYPE html>
<html>
<head>
<title>返回顶部</title>
<meta charset="utf-8" />
<script type="text/javascript" src="jquery-1.8.2.js"></script>
<style type="text/css">
body{
height:2000px;
}
#scrollTop{
position:fixed;
width:36px;
height:65px;
bottom:100px;
right:100px;
text-align:center;
background:url("images/7.png");
color:#FFF;
font-size:12px;
cursor:pointer;
display:none;
}
#scrollTop:hover{
background-position:0px -66px;
}
</style>
</head>
<body>
<div id="scrollTop"></div>
<script type="text/javascript">
$(window).scroll(function(){
if($(window).scrollTop()<=100){
$("#scrollTop").fadeOut(1000);
}else{
$("#scrollTop").fadeIn(1000);
}
})
$("#scrollTop").click(function(){
$(‘body,html‘).animate({scrollTop:0},500);
})
</script>
</body>
</html>
原文：http://www.cnblogs.com/zhangyubao/p/7016856.html