Node.js – REST API

Node.js

REST API

RESTful routing, Express Router, JSON responses, API versioning, CORS setup, and standard status codes in Node.js.

RESTful Route Structure: Standard CRUD routes using Express Router mapped to controller-style handler functions.

📄routes/users.js
JS

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

router.get('/',         userController.index);    // GET    /users
router.post('/',        userController.store);    // POST   /users
router.get('/:id',      userController.show);     // GET    /users/:id
router.put('/:id',      userController.update);   // PUT    /users/:id
router.delete('/:id',   userController.destroy);  // DELETE /users/:id

module.exports = router;

Express Router Mounting: Attach routers to the app with a base path prefix to organise routes cleanly.

📄app.js
JS

const express = require('express');
const app = express();

app.use(express.json());
app.use(express.urlencoded({ extended: true }));

// Mount routers
const userRoutes    = require('./routes/users');
const productRoutes = require('./routes/products');

app.use('/users',    userRoutes);
app.use('/products', productRoutes);

app.listen(3000, () => console.log('Server running on port 3000'));

JSON Response Pattern: Consistent API response wrapper with status, message, and data fields.

📄helpers/response.js
JS

// Helper functions
const ok      = (res, data, message = 'Success')      => res.status(200).json({ success: true,  message, data });
const created = (res, data, message = 'Created')      => res.status(201).json({ success: true,  message, data });
const badReq  = (res, message = 'Bad Request')        => res.status(400).json({ success: false, message, data: null });
const notFound= (res, message = 'Not Found')          => res.status(404).json({ success: false, message, data: null });
const serverErr=(res, message = 'Internal Error')     => res.status(500).json({ success: false, message, data: null });

module.exports = { ok, created, badReq, notFound, serverErr };

// --- Usage in controller ---
// const R = require('../helpers/response');
// exports.show = async (req, res) => {
//   const user = await User.findById(req.params.id);
//   if (!user) return R.notFound(res, 'User not found');
//   return R.ok(res, user);
// };

Common HTTP Status Codes: Quick reference for status codes used in REST APIs.

📄reference – status codes
JS

// 2xx – Success
res.status(200).json(data);   // OK
res.status(201).json(data);   // Created
res.status(204).send();        // No Content (e.g. delete)

// 4xx – Client Error
res.status(400).json({ message: 'Bad Request' });
res.status(401).json({ message: 'Unauthorized' });
res.status(403).json({ message: 'Forbidden' });
res.status(404).json({ message: 'Not Found' });
res.status(422).json({ message: 'Unprocessable Entity' });

// 5xx – Server Error
res.status(500).json({ message: 'Internal Server Error' });
res.status(503).json({ message: 'Service Unavailable' });

API Versioning with Prefix: Group routes under version prefixes (e.g. /api/v1) for backward-compatible evolution.

📄app.js – versioning
JS

const v1Users    = require('./routes/v1/users');
const v1Products = require('./routes/v1/products');
const v2Users    = require('./routes/v2/users');

// Version 1
app.use('/api/v1/users',    v1Users);
app.use('/api/v1/products', v1Products);

// Version 2 (new implementation)
app.use('/api/v2/users', v2Users);

// Or use a router to group them
const v1 = express.Router();
v1.use('/users',    v1Users);
v1.use('/products', v1Products);
app.use('/api/v1', v1);

CORS Setup with cors package: Configure Cross-Origin Resource Sharing to allow specific origins, methods, and headers. Install with npm install cors.

📄app.js – CORS
JS

const cors = require('cors');

// Allow all origins (development only)
app.use(cors());

// Restrict to specific origins (production)
const corsOptions = {
    origin: ['https://myapp.com', 'https://admin.myapp.com'],
    methods: ['GET', 'POST', 'PUT', 'DELETE', 'OPTIONS'],
    allowedHeaders: ['Content-Type', 'Authorization'],
    credentials: true,          // allow cookies / auth headers
    optionsSuccessStatus: 200,
};
app.use(cors(corsOptions));

// Apply CORS only to API routes
app.use('/api', cors(corsOptions), apiRouter);