How to Build a RESTful API with Express
How to scaffold, route, and secure a backend API using Node.js.
Initialize the Express App
Run npm init, install the 'express' package, and create a server.js file. Instantiate the app using const app = express().
Configure Body Parsing
APIs need to read JSON payloads. Add app.use(express.json()) to automatically parse incoming request bodies so they are available on the req.body object.
Define the Resource Routes
Set up endpoints mapping to standard HTTP verbs: GET for fetching, POST for creating, PUT/PATCH for updating, and DELETE for removing (e.g., app.get('/api/users', fetchUsers)).
Extract Logic to Controllers
Do not write database queries inside the route definition. Create a separate 'controllers' folder and write clean functions that accept (req, res, next). Import and attach them to your routes.
Implement Global Error Handling
Create a middleware function taking 4 arguments: (err, req, res, next). Place it at the very bottom of your server.js. In your controllers, use next(err) to instantly route failures to this central handler.
Secure with Helmet
Install the 'helmet' package and add app.use(helmet()). This automatically configures HTTP response headers to protect against common attacks like XSS and Clickjacking.
Start the Server
Call app.listen(PORT) at the bottom of the file to bind the application to a port and begin accepting HTTP requests.
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