JWT Login Example

login.js

const express = require('express')
    , { json } = require('body-parser')
    , jwt = require('jsonwebtoken')
    , to = require('await-to-js')
    , model = require('./model'); // fake model

// This only lives on the server, never the client!
const JWT_SECRET = process.env.JWT_SECRET;

// create a server instance
const app = express();

// parse json bodies as "req.data"
app.use(json()); 

// add the login route handler
app.post('/login', async (req, res) => {
  const { email, password } = req.data;
  
  let err
    , user
    , token;
  
  // Validate the email and password, and grab the user if
  // the email and password are correct;
  [err, user] = await to(model.tryUserLogin(user, password));
  
  if (err) {
    return res.status(401).send({
      message: "Failed to login with provided credentials"
    });
  }
  
  // Create a JWT token, encoding the user's primary
  // key in the body for easy lookup when the token
  // is passed in a subsequent request
  [err, token] = await to(jwt.sign({ id: user.id }, JWT_SECRET));
  
  if (err) {
    // Handle random failures
    // while signing tokens
    return res.status(500).send({
      message: 'An unknown error has occurred'
    });
  }
  
  // Return the token in the body
  return res.status(200).send({
    token
  });
});

// listen on port 8080
app.listen(8080);