返回顶部的一段代码

CSS：

.back_to_top{position:fixed;display:block;right:0;bottom:150px;20px;height:48px;background:url(../Nest/img/top.png) no-repeat;z-index:11; overflow:hidden;}

JQuery:
   

var back_to_top = $("a.back_to_top");
back_to_top.hide();
$(window).scroll(function() {
if ($(window).scrollTop() > 100) {
back_to_top.fadeIn(1500);
}
else {
back_to_top.fadeOut(1000);
}
});

back_to_top.click(function() {
$($.browser.safari || document.compatMode == 'BackCompat' ? document.body : document.documentElement).animate({
scrollTop: 0
}, 200);
return false;
});

Html:

<a class="back_to_top" href="javascript:void(0)"></a>