Fast expressjs app to retrieve OAuth tokens

oauth.js

/**
 * Quick express-app to retrieve OAuth credentials
 * 
 * Run it with $ node index.js
 */

const express = require('express')
const request = require('request')
const app = express()

app.set('port', 3000)

const CLIENT_ID = 'YOUR_CLIENT_ID'
const CLIENT_SECRET = 'YOUR_CLIENT_SECRET'
const SCOPES = 'YOUR_SCOPES'
const AUTHORIZE_URI = 'https://example.com/api/authorize'
const TOKEN_URI = 'https://example.com/api/get_token'
const REDIRECT_URI = `http://localhost:${app.get('port')}/callback`

app.get('/', (req, res) => {
  // Build the auth URL
  const authUrl = AUTHORIZE_URI +
    `?client_id=${encodeURIComponent(CLIENT_ID)}` +
    `&scope=${encodeURIComponent(SCOPES)}` +
    `&redirect_uri=${encodeURIComponent(REDIRECT_URI)}`

  // Redirect the user
  return res.redirect(authUrl)
})

app.get('/callback', (req, res) => {
  if (!req.query.code) {
    return res.send('Something went wrong')
  }
  
  // Exchange authorization code for tokens
  const formData = {
    grant_type: 'authorization_code',
    client_id: CLIENT_ID,
    client_secret: CLIENT_SECRET,
    redirect_uri: REDIRECT_URI,
    code: req.query.code
  }

  request.post(TOKEN_URI, { form: formData }, (err, data) => {
    // Handle the returned tokens
    res.send(data)
  })
})

app.listen(app.get('port'), () => { console.log(`Serving! http://localhost:${app.get('port')}`) } )