jquery给div层加美化滚动条插件

//事件绑定
function myAddEvent(obj, sEvent, fn)
{
	if(obj.attachEvent)
	{
		obj.attachEvent('on'+sEvent, fn);
	}
	else
	{
		obj.addEventListener(sEvent, fn, false);
	}
}

//用id获取元素
function getById(id){
	return document.getElementById(id);
};

//自定义滚动条
function definedScroll(oScroll,oController,oContain,oPassage){
	
	function onMouseWheel(ev){
		var oEvent = ev || event;
		var oB = true;
		
		oB = oEvent.wheelDelta?oEvent.wheelDelta<0:oEvent.detail>0;
		
		if(oB){
			setTop(oController.offsetTop+10);
		}
		else{
			setTop(oController.offsetTop-10)
		}
		
		if(oEvent.preventDefault)
		{
			oEvent.preventDefault();
		}
		
		return false;
	};
	
	myAddEvent(oScroll,'mousewheel',onMouseWheel);
	myAddEvent(oScroll,'DOMMouseScroll',onMouseWheel);
	myAddEvent(oContain,'mousewheel',onMouseWheel);
	myAddEvent(oContain,'DOMMouseScroll',onMouseWheel);
	
	oController.onmousedown = function(ev){
		var oEvent = ev || event;
		var disY = oEvent.clientY - oController.offsetTop;
		
		document.onmousemove = function(ev){
			var oEvent = ev || event;
			var t = oEvent.clientY - disY;
			
			setTop(t);
		};
		
		document.onmouseup = function(){
			document.onmousemove = null;
			document.onmouseup = null;
		};
	};

	function setTop(iTop){
		if(iTop<0){
			iTop = 0;
		}
		else if(iTop>oScroll.offsetHeight - oController.offsetHeight){
			iTop = oScroll.offsetHeight - oController.offsetHeight;
		}
		
		oController.style.top = iTop + "px";
		var scale = iTop/(oPassage.offsetHeight-oContain.offsetHeight);
		
		oPassage.style.top = -(oPassage.offsetHeight-oContain.offsetHeight)*scale + "px";
	}
	
};

window.onload = function(ev){
	var oScroll = getById("scroll");
	var oController = getById("scroll_controler");
	var oContain = getById("scroll_contain");
	var oPassage = getById("scorll_passage");
	
	definedScroll(oScroll,oController,oContain,oPassage);
};