Building a Simple REST API with Express.js — The Right Way

Source: Dev.to

Most Node.js developers start with Express when learning backend development. But even experienced devs often overlook key architectural decisions that impact scalability, maintainability, and security.

Today, we’ll walk through building a clean, modular REST API using Express.js, covering:

• API structure
• Routing
• Controllers
• Middlewares
• Error handling
• Environment configs

🧱 Project Structure

Start with a clean structure:

project-root/
├── controllers/
├── routes/
├── middlewares/
├── models/
├── config/
├── utils/
├── app.js
└── server.js

This modular setup scales well for growing apps.

🧪 Step-by-Step: Create a Simple API

1. Install Express

npm init -y
npm install express dotenv

2. Create server.js

const app = require('./app');
const PORT = process.env.PORT || 5000;

app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

3. Create app.js

const express = require('express');
const app = express();
const userRoutes = require('./routes/userRoutes');

app.use(express.json());
app.use('/api/users', userRoutes);

// Global error handler
app.use((err, req, res, next) => {
  res.status(err.status || 500).json({ message: err.message });
});

module.exports = app;

4. Add a Controller (controllers/userController.js)

exports.getAllUsers = (req, res) => {
  res.json([{ id: 1, name: 'Dipak' }]);
};

5. Add a Route (routes/userRoutes.js)

const express = require('express');
const router = express.Router();
const userController = require('../controllers/userController');

router.get('/', userController.getAllUsers);
module.exports = router;

🛡️ Add Environment Config

• Create a .env file:

PORT=5000
NODE_ENV=development

• Load it in server.js (dotenv is already installed):

require('dotenv').config();

🔒 Add Error Handling Middleware

Create middlewares/errorHandler.js:

const errorHandler = (err, req, res, next) => {
  console.error(err.stack);
  res.status(500).json({ message: 'Something went wrong!' });
};

module.exports = errorHandler;

Register it in app.js:

const errorHandler = require('./middlewares/errorHandler');
app.use(errorHandler);

📦 Bonus: Add CORS & Helmet for Security

npm install cors helmet

const cors = require('cors');
const helmet = require('helmet');

app.use(cors());
app.use(helmet());

✅ Final Output

Run your server:

node server.js

Visit http://localhost:5000/api/users. You’ll get:

[
  { "id": 1, "name": "Dipak" }
]

Clean, modular, and production‑ready!

🔚 Final Thoughts

Building REST APIs in Node.js is simple — but doing it right requires planning. Start clean, modularize your logic, and build secure endpoints. You’re not just learning Express — you’re becoming a better backend engineer.