passport.use(new OAuth2Strategy({
  authorizationURL: 'https://www.example.com/oauth2/authorize',
  tokenURL: 'https://www.example.com/oauth2/token',
  clientID: EXAMPLE_CLIENT_ID,
  clientSecret: EXAMPLE_CLIENT_SECRET,
  callbackURL: "http://localhost:3000/auth/example/callback"
},
function(accessToken, refreshToken, profile, cb) {
  // Do whatever here with the profile
 }
));

app.get('/auth/example/callback',
  passport.authenticate('oauth2', { failureRedirect: '/login' }),
  function(req, res) {
    // Successful authentication, redirect home.
    res.redirect('/');
  });

'use strict';

var OAuth2 = require('oauth').OAuth2;

function getTokenFromCode (code, clientID, clientSecret, authorizationURL, tokenURL) {
  return () => {
    var oAuth2 = new OAuth2(clientID, config.clientSecret,
    '', config.authorizationURL, config.tokenURL);
    var _getOAuthAccessToken = oAuth2.getOAuthAccessToken;
    oAuth2.getOAuthAccessToken = (code, params, callback) => {
      if (responseType) {
        params.response_type = responseType;
      }
      _getOAuthAccessToken.call(oAuth2, code, params, callback);
    };
    return oAuth2;
  };
}