HTTP Server without Express

This exercise helps you understand what Express simplifies.

Goal

Build a small server with these routes:

GET /health
GET /users
POST /users

Starter solution

import http from 'node:http'

const users = []

const server = http.createServer((req, res) => {
  res.setHeader('Content-Type', 'application/json')

  if (req.method === 'GET' && req.url === '/health') {
    res.statusCode = 200
    res.end(JSON.stringify({ status: 'ok' }))
    return
  }

  if (req.method === 'GET' && req.url === '/users') {
    res.statusCode = 200
    res.end(JSON.stringify(users))
    return
  }

  res.statusCode = 404
  res.end(JSON.stringify({ error: 'Not found' }))
})

server.listen(3000)

What to add next

• parse JSON request body for POST /users,
• validate required fields,
• return correct status codes,
• handle bad JSON,
• extract route handling into functions.

Interview angle

Explain that Express automates route matching, body parsing, middleware flow, and error handling, but the foundation is still Node's HTTP request and response model.