server.js

//include request middleware
var request = require('request');

/*
 |--------------------------------------------------------------------------
 | Login with Google
 |--------------------------------------------------------------------------
*/
app.post('/auth/google', function(req, res) {
  var accessTokenUrl = 'https://accounts.google.com/o/oauth2/token';
  var peopleApiUrl = 'https://www.googleapis.com/plus/v1/people/me/openIdConnect';
  var params = {
    code: req.body.code,
    client_id: req.body.clientId,
    client_secret: "YOUR_SECRET_KEY",
    redirect_uri: req.body.redirectUri,
    grant_type: 'authorization_code'
  };

  // Step 1. Exchange authorization code for access token.
  request.post(accessTokenUrl, { json: true, form: params }, function(err, response, token) {
    var accessToken = token.access_token;
    var headers = { Authorization: 'Bearer ' + accessToken };

    // Step 2. Retrieve profile information about the current user.
    request.get({ url: peopleApiUrl, headers: headers, json: true }, function(err, response, profile) {
      if (profile.error) {
        return res.status(500).send({message: profile.error.message});
      }
      console.log(response.body, "auth response");
      var token = jwt.encode(response, params.client_secret);

      // Step 3. Send response to front-end.
      res.send({ token: token });

    });
  });
});