JS判断IE关闭代码

js 代码

<script language="javascript">

window.onbeforeunload = function()
{   var n = window.event.screenX - window.screenLeft;
    var b = n > document.documentElement.scrollWidth-20;
 if(b && window.event.clientY < 0 || window.event.altKey)
 {
 window.event.returnValue = "1111";
 }
}
</script>