基于jquery的返回顶部效果（兼容IE6）

<div class="scroll"></div>
<script type="text/javascript" src="../skins/css/jQuery.js" charset="UTF-8"></script>
<script type="text/javascript" src="../skins/css/top.js" charset="UTF-8"></script>

.scroll{
background:url(../image/scroll.gif) no-repeat center top transparent;
bottom:100px;
cursor:pointer;
height:67px;
width:18px;
position:fixed;
_position:absolute; /*兼容IE6*/
_top: expression(eval(document.documentElement.scrollTop)+700); /*700为图片距离顶部的设定距离，可以修改。不加700则图片紧贴在顶部滚动*/
}
html{_text-overflow:ellipsis;} /*解决IE6下图片抖动*/

$(document).ready(function(){
var show_delay;
var scroll_left=parseInt((document.body.offsetWidth-960)/2)+961; //960为页面宽度
$(".scroll").click(function (){
document.documentElement.scrollTop=0;
document.body.scrollTop=0;
});
$(window).resize(function (){
scroll_left=parseInt((document.body.offsetWidth-960)/2)+961;
$(".scroll").css("left",scroll_left);
});
reshow(scroll_left,show_delay);
});
function reshow(marign_l,show_d) {
$(".scroll").css("left",marign_l);
if((document.documentElement.scrollTop+document.body.scrollTop)!=0)
{
$(".scroll").css("display","block");
}
else
{
$(".scroll").css("display","none");}
if(show_d) window.clearTimeout(show_d);
show_d=setTimeout("reshow()",500);
}