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();

        }

    }