var objWin;         function isOpen(id) {             //目标页面             var target = "pop.html?id="+id;             //判断是否打开             if (objWin == null || objWin.closed) {                 objWin = window.open(target);             } else {                 objWin.location.replace(target);             }             //objWin.focus();         }                               
      
       A页面1
       
        
       
        A页面2
        
        
        
         A页面3