Express.js Intro

Relax. We'll talk through this in plain words — no textbook voice.

Express.js is a framework that makes writing Node.js web servers much easier. Splitting routes with the raw http module means more code, but with Express, app.get(), app.post(), and middleware let you manage everything effortlessly.

javascript

const express = require('express');

const app = express();
const port = 3000;

app.get('/', (req, res) => {
  res.send('Hello from Express!');
});

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

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

express() creates an Express app. app.get('/') is the home route, so when the browser visits the home path, it sends back text. The /health route is a small API endpoint that returns a JSON response.

You should see

Express app running at http://localhost:3000 GET /health result: { "status": "ok", "service": "nodejs-tutorial" }

Info

Route order matters in Express. Put specific routes near the top, and keep fallback/404 routes at the very bottom.

Easy traps

If you run the app without npm install express, you'll get a "Cannot find module 'express'" error.

Exercise

Express is widely used in projects like dashboard backends, auth servers, REST APIs, file upload APIs, and webhook receivers.

You'll know it worked when: