返回顶部代码-copy自51cto

 看到51cto博客新增了返回顶部按钮，这很实用，正好自己也在捣鼓着一个破网站，就查看源码，加上呗！

<style>
	.backToTop {
	display: none;
	WIDTH: 45px;
	height:45px;
	BOTTOM: 20px;
	position: fixed;
	_position: absolute;
	right: 140px;
	bottom: 10px;
	_bottom: "auto";
	cursor: pointer;
	opacity: .6;
	filter: Alpha(opacity=60);
	text-indent:-9999px;
	}
	.tops { background:url(/images/tops.jpg) no-repeat center center; }
	</style>
	<script type="text/javascript">
	(function() {
	var backToTopTxt = "返回顶部", backToTopEle = $('<div class="backToTop tops"></div>').appendTo($("body"))
	.text(backToTopTxt).attr("title", backToTopTxt).click(function() {
	$("html, body").animate({ scrollTop: 0 }, 520);
	}), backToTopFun = function() {
	var st = $(document).scrollTop(), winh = $(window).height();
	(st > 0)? backToTopEle.show(): backToTopEle.hide();
	//IE6下的定位
	if (!window.XMLHttpRequest) {
	backToTopEle.css("top", st + winh - 60);
	}
	};
	$(window).bind("scroll", backToTopFun);
	$(function() { backToTopFun(); });
	})();
	</script>