ReferenceError:未在server.js passportjs定义用户

npm install passport

const passport = require('passport');

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const userSchema = new Schema({
  username: String,
  password: String
});

const User = mongoose.model('User', userSchema);

const LocalStrategy = require('passport-local').Strategy;

passport.use(new LocalStrategy(
  function(username, password, done) {
    User.findOne({ username: username }, function(err, user) {
      if (err) { return done(err); }
      if (!user) { return done(null, false); }
      if (!user.validPassword(password)) { return done(null, false); }
      return done(null, user);
    });
  }
));

app.post('/login', passport.authenticate('local', { successRedirect: '/', failureRedirect: '/login' }));