js 禁止鼠标滚动

window.onload=function(){    var oDiv=document.getElementById("top");    oDiv.onmouseover = function () {        if(window.event){            document.onmousewheel = function () {                window.event.returnValue="false";                return false;            }        }else{            oDiv.addEventListener("DOMMouseScroll",function(ev){ev.preventDefault();} , false);        }    };    oDiv.onmouseout=function(){        document.onmousewheel=null;    }}