auth.js

/**
 * auth.js module defines the: POST /login -ENDPOINT: to login users implementing a JWT strategy-
 * @module auth
 */
const jwtSecret = 'your_jwt_secret'; // This has to be the same key used in the JWTStrategy

const jwt = require('jsonwebtoken'),
  passport = require('passport');

require('./passport'); // Your local passport file

let generateJWTToken = (user) => {
  return jwt.sign(user, jwtSecret, {
    subject: user.username, // This is the username you’re encoding in the JWT
    expiresIn: '7d', // This specifies that the token will expire in 7 days
    algorithm: 'HS256', // This is the algorithm used to “sign” or encode the values of the JWT
  });
};

// POST /login --> Endpoint to authenticate registered user & send back a generated JWT
module.exports = (router) => {
  router.post('/login', (req, res) => {
    // We implement LocalStrategy defined in passport.js
    passport.authenticate('local', { session: false }, (error, user, info) => {
      if (error || !user) {
        return res.status(400).json({
          message: 'Something is not right',
          user: user,
        });
      }
      req.login(user, { session: false }, (error) => {
        if (error) {
          res.send(error);
        }
        let token = generateJWTToken(user.toJSON());
        return res.json({ user, token }); //ES6 object: {user: user, token: token}
      });
    })(req, res);
  });
};