不会提示是否关闭浏览器 IE6、IE7、FF通用代码

start = setInterval('CloseWin();', 2000);

      function CloseWin() //这个不会提示是否关闭浏览器  IE6、IE7、FF通用代码：
      {

          if (document.readyState == "complete") {
              try {
                  clearInterval(start); //执行成功，清除监听
                  window.opener = null;
                  //window.opener=top;   
                  window.open("", "_self");
                  window.close();
              }
              catch (err) {
                  alert(err);
              }

          }
        
      }