JS打开url并避免重复打开

var objWin;
function inputYX() {
      //目标页面
      var target = '要打开的url;
      //判断是否打开
      if (objWin == null || objWin.closed) {
          objWin = window.open(target);
       } else {
          objWin.location.replace(target);//替换页面
//        将之前打开的关闭并重新打开
//        objWin.close();
//        objWin = window.open(target);
        }      
 }