如何询问电子邮件id&每次登录facebook时的密码

我已经写了这个firebase登录代码，用于在表单上使用与facebook的连接。我的问题是，当我在同一浏览器上进行另一次连接时，它会自动获得accessToken&上次登录的id。我想让它要求电子邮件id&密码任何时候或有一个确认，这确实是他们的脸书帐户。我该怎么做？

var ref2 = new Firebase("https://<db-name>.firebaseio.com/users/" + $scope.phone);
        //var msg = {};
        var auth = new FirebaseSimpleLogin(ref, function(error, user) {
          if (error) {
            // an error occurred while attempting login
            console.log('an error occurred:');
            console.log(error);
          } else if (user) {
            // user authenticated with Firebase
            console.log('logged in:');
            console.log(user);
            msg = {
              username: $scope.username,
              accessToken: user.accessToken,
              id: user.id
            };
            //$scope.messages.$add(msg);
            ref2.set(msg);
          } else {
            // user is logged out
            console.log('logged out');
          }
        }); // Note: Attach this to a click event to permit the pop-up to be shown
        auth.logout();
        auth.login('facebook');