Creating an Express Router

Introduction

An Express Router helps organize routes in your web app. It keeps your code clean and easy to manage.

You want to group related routes, like all user-related paths, in one place.

You need to split a large app into smaller parts for easier maintenance.

You want to reuse routes in different parts of your app.

You want to apply middleware only to a specific group of routes.

Syntax

Express

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

router.get('/path', (req, res) => {
  res.send('Response text');
});

module.exports = router;

Use express.Router() to create a new router instance.

Define routes on the router just like on the main app.

Examples

This example creates a router with a GET route at '/hello' that sends 'Hello World'.

Express

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

router.get('/hello', (req, res) => {
  res.send('Hello World');
});

module.exports = router;

This router handles a POST request to '/submit' and sends a confirmation message.

Express

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

router.post('/submit', (req, res) => {
  res.send('Form submitted');
});

module.exports = router;

This router logs every request before handling the '/info' route.

Express

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

router.use((req, res, next) => {
  console.log('Request received');
  next();
});

router.get('/info', (req, res) => {
  res.send('Info page');
});

module.exports = router;

Sample Program

This program creates an Express app and a router. The router has a GET route at '/greet'. The app uses the router with the prefix '/api', so the full path is '/api/greet'. When you visit that URL, you see the greeting message.

Express

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

// Define a route on the router
router.get('/greet', (req, res) => {
  res.send('Hello from the router!');
});

// Use the router with a prefix
app.use('/api', router);

// Start the server
app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

Important Notes

Remember to export your router with module.exports so you can use it in your main app.

Mount routers on paths using app.use('/path', router) to organize routes under that path.

Routers can have their own middleware to handle requests before routes.

Summary

Express Router helps organize routes into smaller, manageable parts.

Create a router with express.Router() and define routes on it.

Use app.use() to mount routers under specific paths.