app.js

var express = require('express')
  , mongoose = require('mongoose')
  , passport = require('passport')
  , util = require('util')
  , TwitterStrategy = require('passport-twitter').Strategy
  , Schema = mongoose.Schema;

var TWITTER_CONSUMER_KEY = ""
var TWITTER_CONSUMER_SECRET = "";

var UserSchema = new Schema({
  provider: String,
  uid: String,
  name: String,
  image: String,
  created: {type: Date, default: Date.now}
});

mongoose.connect('mongodb://localhost/twitter-mongo');
mongoose.model('User', UserSchema);

var User = mongoose.model('User');

passport.use(new TwitterStrategy({
    consumerKey: TWITTER_CONSUMER_KEY,
    consumerSecret: TWITTER_CONSUMER_SECRET,
    callbackURL: "http://localhost:3000/auth/twitter/callback"
  },
  function(token, tokenSecret, profile, done) {
    User.findOne({uid: profile.id}, function(err, user) {
      if(user) {
        done(null, user);
      } else {
        var user = new User();
        user.provider = "twitter";
        user.uid = profile.id;
        user.name = profile.displayName;
        user.image = profile._json.profile_image_url;
        user.save(function(err) {
          if(err) { throw err; }
          done(null, user);
        });
      }
    })
  }
));

passport.serializeUser(function(user, done) {
  done(null, user.uid);
});

passport.deserializeUser(function(uid, done) {
  User.findOne({uid: uid}, function (err, user) {
    done(err, user);
  });
});

var app = express.createServer();

// configure Express
app.configure(function() {
  app.set('views', __dirname + '/views');
  app.set('view engine', 'ejs');
  app.use(express.logger());
  app.use(express.cookieParser());
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use(express.session({ secret: 'keyboard cat' }));
  app.use(passport.initialize());
  app.use(passport.session());
  app.use(app.router);
  app.use(express.static(__dirname + '/public'));
});

app.get('/', function(req, res){
  res.render('index', { user: req.user });
});

app.get('/auth/twitter',
  passport.authenticate('twitter'),
  function(req, res){
    // The request will be redirected to Twitter for authentication, so this
    // function will not be called.
  });

app.get('/auth/twitter/callback', 
  passport.authenticate('twitter', { failureRedirect: '/login' }),
  function(req, res) {
    res.redirect('/');
  });

app.get('/logout', function(req, res){
  req.logout();
  res.redirect('/');
});

app.listen(3000);

function ensureAuthenticated(req, res, next) {
  if (req.isAuthenticated()) { return next(); }
  res.redirect('/')
}