How to differentiate Login from Sign up when using PassportJS for Facebook

Nevermind, found the answer. Here is the updated code below. Pay attention to the use of passReqToCallback and req.session.newu

passport.use(new FacebookStrategy(
  {
    clientID: 'XXX',
    clientSecret: 'XXX',
    callbackURL: "https://www.XXX.co/auth/facebook/callback",
    passReqToCallback: true
  },
  function(req, accessToken, refreshToken, profile, done) {
    //console.log(profile);
    User.findOne({ uid: profile.id }, function(err, uInfo) {
      if(err) console.log('Error: '+err);
      else{
        if(uInfo){
          done(err, uInfo);
        }
        else{
            var newUser = new User ({
              uid: profile.id,
              email:profile.emails[0].value,
              ref: 'Facebook'
            });
            // Saving it to the database.  
            newUser.save(function (err,uInfo) {
              if (err) console.log ('Error on save!');
              req.session.newu=true;
              done(err, uInfo);
            });
        }
      }
    })
  }
));

app.get('/auth/facebook', passport.authenticate('facebook',{ scope: 'email' }));
app.get('/auth/facebook/callback',function(req, res, next) {

  passport.authenticate('facebook', function(err, user, info) {
    if (err) { return next(err); }
    if (!user) { return res.redirect('/login'); }
    req.logIn(user, function(err) {
      if (err) { return next(err); }
      var redLink = '/dashboard';
      if(req.session.newu)redLink = '/dashboard?newu'
      return res.redirect(redLink);
    });
  })(req, res, next);

});

An existing user will be redirected to /dashboard and a new user will be redirected to /dashboard?newu Google Analytics doesn't need 2 different urls, it just needs a query string. When I set up the url goal, I selected url start with /dashboard?newu.

Hope this helps