index.js

var google = require('googleapis');
var OAuth2 = google.auth.OAuth2;

// constants
var CLIENT_ID = '312634809793-4d4baf8u62ck2l4s7uucamp175m9q49p.apps.googleusercontent.com';
var CLIENT_SECRET = 'My Client Secret';
var REDIRECT_URL = 'http://localhost:3000/oauth2callback'; // registered with the developer console

var oauth2Client = new OAuth2(CLIENT_ID, CLIENT_SECRET, REDIRECT_URL);

var url = oauth2Client.generateAuthUrl({
	access_type: 'offline',
	scope: 'https://www.googleapis.com/auth/calendar.readonly' // which api I will be using
});

console.log('url: ' + url); // works

/* GET home page. */
router.get('/', function(req, res) {
  res.render('index', { url: url });
});

router.get('/oauth2callback', function(req, res) {
	var code = req.query.code;

	oauth2Client.getToken(code, function(err, tokens) {
	  // Now tokens contains an access_token and an optional refresh_token. Save them.
	  if (!err) {
	    oauth2Client.setCredentials(tokens);

	    	var calendar = google.calendar({ version: 'v3', auth: oauth2Client });
		console.log('calendar: ' + JSON.stringify(calendar)); // all well except no actualy values
		console.log('events: ' + JSON.stringify(calendar.events)); // --> events: {}

		var list = calendar.events.list({
			calendarId: '[email protected]',
			maxResults: 10
		}, function(err, results) {
			if (err) return console.log(err);
				res.render('index', { url: url, events: results });
		});
	  }
	});
	
});