Node.js Router

Node.js Router

In Node.js web applications, routing refers to determining how an application responds to a client request to a particular endpoint, which is a URI (or path) and a specific HTTP request method (GET, POST, and so on).

Basic Routing with Express

While you can implement routing with the built-in http module, it’s very common to use a framework like Express to handle routing because it provides a simpler and more robust set of features.

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

// Respond with 'Hello World!' on the homepage
app.get('/', (req, res) => {
  res.send('Hello World!');
});

// Respond to POST request on the root route
app.post('/', (req, res) => {
  res.send('Got a POST request');
});

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`);
});

Creating Modular Routes with express.Router

As your application grows, defining all routes in a single file becomes unmanageable. You can use the express.Router class to create modular, mountable route handlers. A Router instance is often referred to as a “mini-app”.

Example: Users Router

Create a router file named users.js:

const express = require('express');
const router = express.Router();

// Middleware specific to this router
router.use((req, res, next) => {
  console.log('Time: ', Date.now());
  next();
});

// Define the home page route
router.get('/', (req, res) => {
  res.send('Users home page');
});

// Define the about route
router.get('/about', (req, res) => {
  res.send('About users');
});

module.exports = router;

Load the router module in your main application:

const express = require('express');
const app = express();
const users = require('./users');

// Mount the router on the /users path
app.use('/users', users);

Now, the application handles requests to /users and /users/about by delegating them to the users router module.