GitHub Login OAuth example with Node.js and Express

index.js

const { createOAuthAppAuth } = require("@octokit/auth-oauth-app")

const express = require('express')
const app = express()
const port = 3000

const clientId = '123'
const clientSecret = '456'
const authUrl = `https://github.com/login/oauth/authorize?client_id=${clientId}&redirect_uri=http://localhost:3000/login`
const body = `<button onclick="location.href='${authUrl}'">Login with GitHub</button>`

/**
 * 1. Open http://localhost:3000/
 * 2. Click on "Login with GitHub" -> Authorize App
 * 3. You'll be redirected to http://localhost:3000/login?code=123samplecode
 * 4. In the browser console run: `response = await fetch(`/login?code=${(new URLSearchParams(window.location.search)).get('code')}`, { method: 'POST' }); await response.json()`
 * 5. Browser console should output object with `token` that can now be used to authenticate with the GitHub API
 */

/**
 * Page with "Login with GitHub" button
 */
app.get('/', (req, res) => res.send(body))

/**
 * Redirect page: Run step 4 on this page
 */
app.get('/login', (req, res) => {
  res.send('Logging in')
})

/**
 * This is the POST endpoint that gets the authentication token from GitHub and which we call in step 4
 */
app.post('/login', async (req, res) => {
  const auth = createOAuthAppAuth({
    clientId,
    clientSecret
  })

  console.log(auth)

  const tokenAuthentication = await auth({
    type: 'token',
    code: req.query.code
  })

  console.log(tokenAuthentication)

  res.send(tokenAuthentication)
})

app.listen(port, () => console.log(`Example app listening at http://localhost:${port}`))

package.json

{
  "name": "github-login-oauth-example",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "nodemon index.js",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@octokit/auth-oauth-app": "^3.0.5",
    "express": "^4.17.1",
    "nodemon": "^2.0.4"
  }
}