function goTop(acceleration, time) {
	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;

	// 滾動條到頁面頂部的水平距離
	var x = Math.max(x1, Math.max(x2, x3));
	// 滾動條到頁面頂部的垂直距離
	var y = Math.max(y1, Math.max(y2, y3));

	// 滾動距離 = 目前距離 / 速度, 因為距離原來越小, 速度是大於 1 的數, 所以滾動距離會越來越小
	var speed = 1 + acceleration;
	window.scrollTo(Math.floor(x / speed), Math.floor(y / speed));

	// 如果距離不為零, 繼續調用迭代本函數
	if(x > 0 || y > 0) {
		var invokeFunction = "goTop(" + acceleration + ", " + time + ")";
		window.setTimeout(invokeFunction, time);
	}
}


var isIE=!!window.ActiveXObject;
var isIE6=isIE&&!window.XMLHttpRequest;
//IE6不處理
if(!isIE6){
window.onscroll = function(){
   var scrollElement = document.getElementById('scroll');
   if(scrollElement){
		scrollElement.style.display = (document.documentElement.scrollTop+document.body.scrollTop)?'block':'none'
   }
	}
}