页面关闭时触发事件

<script language="javascript">
window.onbeforeunload = function()   
{   
      if(!(event.clientX>document.body.clientWidth&&event.clientY<0||event.altKey))   
      {   
  //在刷新、或以_self方式转到其它页面、或用ALT+CTLR+DEL关闭时触发；  
  //代码
       }
      else
      {
         //点击工具栏上的[X]按钮、或ALT+F4关闭时触发 
      }
}
</script>

window.onbeforeunload   =   function()   
        {   
            if((event.clientX>document.body.clientWidth&&event.clientY<0)||event.altKey)   
            {          
                 //alert("关闭触发");
            }
            else
            {
                 //alert("刷新触发");
            }
        }