First, we need to add our Google-specific information to our config. Open config.js and add the following lines:

routes: {
    login: '/account/login',
    logout: '/account/logout',
    chat: '/chat',    facebookAuth: '/auth/facebook',
    facebookAuthCallback: '/auth/facebook/callback',
    googleAuth: '/auth/google',
    googleAuthCallback: '/auth/google/callback'
  },
//host and facebook
google: {
    clientID: 'YOUR_GOOGLE_ID',
    clientSecret: 'YOUR_GOOGLE_SECRET'
  }

We haven't added anything different. We just had to create the two Google authentication routes and add the ID and secret.

The package we will use is passport-google-oauth. This should be installed already at this point through npm install. Notice that this is not passport-google. That package is used to authenticate with OpenID, and we want to use OAuth2.

Open index.js present in the passport folder and add a reference to our Google strategy as follows:

//other variable declarations...