CSS
<style>
<!--
.back-to {
bottom: 35px;
overflow: hidden;
position: fixed;
right: 10px;
width: 110px;
z-index: 999;
}
.back-to .back-top {
background: url("http://static.wetui.com/img/page-back-top.png") no-repeat scroll 0 0 transparent;
display: block;
float: right;
height: 50px;
margin-left: 10px;
outline: 0 none;
text-indent: -9999em;
width: 50px;
}
.back-to .back-top:hover {
background-position: -50px 0
}
-->
</style>
HTML
<div style="display:none;" class="back-to" id="toolBackTop">
<a title="返回顶部" onclick="window.scrollTo(0,0);return false;" href="#top" class="back-top">
返回顶部</a>
</div>
[先需要引入jQuery库哟！]JS
$j(document).ready(function () {
var bt = $j('#toolBackTop');
var sw = $j(document.body)[0].clientWidth;
var limitsw = (sw - 840) / 2 - 80;
if (limitsw > 0){
limitsw = parseInt(limitsw);
bt.css("right",limitsw);
}
$j(window).scroll(function() {
var st = $j(window).scrollTop();
if(st > 30){
bt.show();
}else{
bt.hide();
}
});
});
Image