<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<style>
*{
margin:0;
padding:0;
}
body{
height:1900px;
}
.cc{
position:absolute;
width:80px;
height:120px;/*高度值可设置，也可通过内容自动填充*/
background:green;
right:0;
top:50%;
}
</style>
<script src="jquery-1.11.3.min.js"></script>
<script>
$(function(){
function roll(){
var $win=$(window).height(),$scroll=$(document).scrollTop(),$cc=$(".cc"),$height=$cc.height();
$cc.animate({"top":$win/2+$scroll-$height/2},100)
}
roll();
$(window).on("scroll",function(){
roll();
})
})
</script>
</head>
<body>
<div class="cc"></div>
</body>
</html>
