NodeJS Passport TypeError：undefined不是函数

Question

我正在使用node.js的护照模块，我收到以下错误：

TypeError: undefined is not a function
at module.exports (C:\cygwin64\home\Home\gethweb\routes\index.js:21:33)
at Layer.handle [as handle_request] (C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\layer.js:95:5)
at trim_prefix (C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\index.js:312:13)
at C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\index.js:280:7
at Function.process_params (C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\index.js:330:12)
at next (C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\index.js:271:10)
at C:\cygwin64\home\Home\gethweb\node_modules\connect-flash\lib\flash.js:21:5
at Layer.handle [as handle_request] (C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\layer.js:95:5)
at trim_prefix (C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\index.js:312:13)
at C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\index.js:280:7
at Function.process_params (C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\index.js:330:12)
at next (C:\cygwin64\home\Home\gethweb\node_modules\express\lib\router\index.js:271:10)
at SessionStrategy.strategy.pass (C:\cygwin64\home\Home\gethweb\node_modules\passport\lib\middleware\authenticate.js:318:9)
at SessionStrategy.authenticate (C:\cygwin64\home\Home\gethweb\node_modules\passport\lib\strategies\session.js:67:10)
at attempt (C:\cygwin64\home\Home\gethweb\node_modules\passport\lib\middleware\authenticate.js:341:16)
at authenticate (C:\cygwin64\home\Home\gethweb\node_modules\passport\lib\middleware\authenticate.js:342:7)

以下是我的index.js文件的相关部分：

var express = require('express');
var passport = require('passport');
router = express.Router();

module.exports = function(passport) {

router.get('/', function(req, res) {
    res.render('index', { message: req.flash('message') });
});

router.post('/login', passport.authenticate('login', {
    successRedirect: '/home',
    failureRedirect: '/',
    failureFlash : true 
}));

router.get('/signup', function(req, res) {
    res.render('register',{message: req.flash('message')});
});

router.post('/signup', passport.authenticate('signup', {
    successRedirect : '/home',
    failureRedirect : '/signup',
    failureFlash : 'true'
}));

return router;
};

编辑：

init.js：

var login = require('./login.js');
var signup = require('./signup.js');
var User = require('../models/user');

module.exports = function(passport) {

passport.serializeUser(function(user, done) {
    console.log('serializing user: '); console.log(user);
    done(null, user._id);
});

passport.deserializeUser(function(id, done) {
    User.findById(id, function(err, user) {
        console.log('deserializing user: ', user);
        done(err, user);
    });
});

login(passport);
signup(passport);
}

和signup.js：

var LocalStrategy = require('passport-local').Strategy;
var User = require('../models/user');
var bCrypt = require('bCrypt-nodejs');

module.exports  = function(passport) {
passport.use('signup', new LocalStrategy({
    passReqToCallback : true
},
function(req, username, password, done) {

    findOrCreateUser = function() {
        User.findOne({ 'username' : username }, function(err, user) {
            if (err) {
                console.log('Error in SignUp: '+err);
                return done(err);
            }

            if (user) {
                console.log('User already exists with username' + username);
                return done(null, false, req.flash('message', 'User Already Exists'));
            } else {
                var newUser = new User();

                newUser.username = username;
                newUser.password = createHash(password);
                newUser.email = req.param('email');
                newUser.firstName = req.param('firstName');
                newUser.lastName = req.param('lastName');

                newUser.save(function(err) {
                    if (err) {
                        console.log('Error in Saving user: ' + err);
                        throw err;
                    };
                    console.log('User Registration successful');
                    return done(null, newUser);
                });
            }
        });
    };

    process.nextTick(findOrCreateUser);

    })
);

var createHash = function(password) {
    return bCrypt.hashSync(password, bCrypt.genSaltSync(10), null);
}
}

有谁能告诉我导致错误的原因是什么？非常感谢。