<!-- to top edit by inksci--->	
<style>	
#to_top{
	position:fixed;
	bottom:100px;
	right:0px;
	width:60px;
	height:60px;
	font-size:14px;
	line-height:60px;
	text-align:center;
	background-color:black;
	color:rgb(246,168,0);
	cursor:pointer;
}
</style>	
<div onclick="top_it()" id="to_top">
TOP
</div>	
<script type="text/javascript"> 
var oTop = document.getElementById("to_top");
oTop.style.display="none";
var top_break=false;
/** 
* 回到页面顶部 
* @param acceleration 加速度 
* @param time 时间间隔 (毫秒) 
**/
var save_scrolltop=100000000000000;
window.onscroll = function(){


    var scrolltop = document.documentElement.scrollTop || document.body.scrollTop;
    if(scrolltop>300){
		oTop.style.display="block";
	}else{
		oTop.style.display="none";
	}
if(scrolltop>save_scrolltop)
{
top_break=true;
}
save_scrolltop=scrolltop;
}
function top_it(){
top_break=false;
goTop();return false;
}
function goTop(acceleration, time) {
if(top_break){
	return;
} 
//oTop.style.display="none";
acceleration = acceleration || 0.1; 
time = time || 16; 
 
var x1 = 0; 
var y1 = 0; 
var x2 = 0; 
var y2 = 0; 
var x3 = 0; 
var y3 = 0; 
 
if (document.documentElement) { 
x1 = document.documentElement.scrollLeft || 0; 
y1 = document.documentElement.scrollTop || 0; 
} 
if (document.body) { 
x2 = document.body.scrollLeft || 0; 
y2 = document.body.scrollTop || 0; 
} 
var x3 = window.scrollX || 0; 
var y3 = window.scrollY || 0; 
 
// 滚动条到页面顶部的水平距离 
var x = Math.max(x1, Math.max(x2, x3)); 
// 滚动条到页面顶部的垂直距离 
var y = Math.max(y1, Math.max(y2, y3)); 
 
// 滚动距离 = 目前距离 / 速度, 因为距离原来越小, 速度是大于 1 的数, 所以滚动距离会越来越小 
var speed = 1 + acceleration; 
window.scrollTo(Math.floor(x / speed), Math.floor(y / speed)); 
 
// 如果距离不为零, 继续调用迭代本函数 
if(x > 0 || y > 0) { 
var invokeFunction = "goTop(" + acceleration + ", " + time + ")"; 
window.setTimeout(invokeFunction, time); 
} 
} 
</script>	
<!-- to top edit by inksci--->