Window.Event 多浏览器兼容

//tip show
function showTip(boxID,tipText,evt){
        //方法中必须传event作为参数，FF下根据window.event获取对象
        var evt = (evt) ? evt : ((window.event) ? window.event : null);
        
        var content=document.getElementById(boxID);
        content.innerHTML = tipText;
        content.style.display="block";
        var x=document.documentElement.scrollLeft + evt.x;
        var y=document.documentElement.scrollTop + evt.clientY ;
                
        content.style.left = x + "px";
        content.style.top = y + "px";
}

//tip hide        
function hideTip(boxID){
            var content=document.getElementById(boxID);
            content.style.display="none";
}

 

<div id="text" onmouseover="showTip('tipBox','Show Tip Box!',event)" onmouseout="hideTip('tipBox')" >
        Show Tip Box
</div>
    <p>this para1</p><p>this para2</p>
    <p>this para1</p><p>this para2</p>
<div id="tipBox" style="position:absolute;">
</div>