捕获窗体关闭事件

?

window.onbeforeunload = function()

  {

      if(document.body.offsetWidth-50 < event.clientX && event.clientY<0)

      {

          Close();

      }

      else if(event.clientX>document.body.clientWidth && event.clientY<0 ||event.altKey)

      {    

         Close();

      }

  }