function getScroll(id){
	var obj = document.getElementById(id);
	var timer = null;
	positionFixed(obj);
	if(obj){
		obj.style.display = 'none';
		window.onscroll=function(){
			getScrollTop() > 0 ? obj.style.display = "block" : obj.style.display = "none";
		}
		obj.onclick=function(){
			var timer = setInterval(sMove,10);
			function sMove(){
				setScrollTop(getScrollTop() / 1.5);
				if(getScrollTop() < 1)clearInterval(timer);
			}
		}
	}
}
//判断IE6
function positionFixed(obj){
	var iE6 = !-[1,] && !window.XMLHttpRequest;
	if(obj){
		var top = obj.offsetTop;
		if(iE6){
			document.documentElement.style.textOverflow = "ellipsis";
			obj.style.position = "absolute";
			obj.style.setExpression("top", "eval(documentElement.scrollTop + " + top + ') + "px"');
		}
	}
}
//获取滚动条Top
function getScrollTop(){
	return document.documentElement.scrollTop || document.body.scrollTop;
}
//回到顶部
function setScrollTop(value){
	document.documentElement.scrollTop = value;
	document.body.scrollTop = value;
}
window.onload = function(){
	getScroll('div1');
};