api/strategies/facebookStrategy.js

const FacebookStrategy = require('passport-facebook').Strategy;
const User = require('../models/User');
const config = require('../../config/loader');
const domains = config.domains;

// facebook strategy
const facebookLogin = async () =>
  new FacebookStrategy(
    {
      clientID: process.env.FACEBOOK_APP_ID,
      clientSecret: process.env.FACEBOOK_SECRET,
      callbackURL: `${domains.server}${process.env.FACEBOOK_CALLBACK_URL}`,
      proxy: true,
      // profileFields: [
      //   'id',
      //   'email',
      //   'gender',
      //   'profileUrl',
      //   'displayName',
      //   'locale',
      //   'name',
      //   'timezone',
      //   'updated_time',
      //   'verified',
      //   'picture.type(large)'
      // ]
    },
    async (accessToken, refreshToken, profile, done) => {
      console.log('facebookLogin => profile', profile);
      try {
        const oldUser = await User.findOne({ email: profile.emails[0].value });

        if (oldUser) {
          console.log('FACEBOOK LOGIN => found user', oldUser);
          return done(null, oldUser);
        }
      } catch (err) {
        console.log(err);
      }

      // register user
      try {
        const newUser = await new User({
          provider: 'facebook',
          facebookId: profile.id,
          username: profile.name.givenName + profile.name.familyName,
          email: profile.emails[0].value,
          name: profile.displayName,
          avatar: profile.photos[0].value,
        }).save();

        done(null, newUser);
      } catch (err) {
        console.log(err);
      }
    },
  );

module.exports = facebookLogin;