passportoauth2.js

passport.use(new FitbitStrategy({
        clientID:     process.env.ID,
        clientSecret: process.env.SECRET,
        callbackURL: host + "/auth/callback"
    },
    function(accessToken, refreshToken, profile, done) {
        done(null, {token: accessToken});
    }
));

server.get('/',
    passport.authenticate('fitbit', {scope: ['weight', 'profile']}));

server.get('/auth/callback',
    passport.authenticate('fitbit', { failureRedirect: '/login' }),
    function(req, res) {
        console.log(req.user);
        res.redirect('/app.html');
    }
);