← Node.js Backend Fundamentals

Lesson 4 of 6

Building an Express Server

Express is the most popular web framework for Node.js.

import express from 'express';

const app = express();
app.use(express.json());

app.get('/api/health', (req, res) => {
  res.json({ status: 'ok' });
});

app.listen(4000, () => console.log('Listening on :4000'));

Server code runs in Node.js, not in the browser playground, you'll run this for real in the final project.

Key concepts

Routes map an HTTP method + path to a handler.
Middleware functions run in order before your handler (parsing, auth, logging).
req / res, the request and response objects.