Express.js Router

Posted in Express Tutorial

Updated on Sep 13, 2024

By Mari Selvan

👁️ 123 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the landscape of Express.js, the Router is a powerful tool that aids in organizing and modularizing route handling. It allows developers to create modular sets of routes, enhancing code organization and maintainability.

This page serves as a comprehensive guide to the Router in Express.js, providing insights into its structure, usage, and best practices.

🧐 What is the Express.js Router?

The Router in Express.js is a middleware that helps in defining and organizing routes in a more modular and structured manner. It allows developers to group related routes together and provides a mechanism for creating a mini-application with its own set of routes and middleware.

The Router plays a key role in breaking down the application into smaller, manageable components, improving code readability and maintainability.

🏁 Initializing the Express.js Router

To utilize the Router, it needs to be initialized using the express.Router() method. This method returns an instance of a router that can be used to define routes and middleware specific to that router.

express-router.js

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

This creates an instance of the Router, and you can now define routes and middleware for this specific router.

🧠 Anatomy of the Express.js Router

Basic Structure:

The Router object is similar to the main app object but provides a more focused scope for defining routes and middleware. Routes can be defined in the same way as in the main application, making it easy to group related functionality.

🔑 Key Features and Methods

router.get(), router.post(), etc.:

The Router object allows you to define routes using HTTP methods such as get, post, put, delete, etc. This is similar to how routes are defined in the main application using the app object.
router.js
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```
// Define a route using the Router
router.get('/users', (req, res) => {
  res.send('List of users');
});
```
Middleware with router.use():

Middleware functions can be applied to a specific router using the router.use() method. This allows you to add middleware that will only affect routes defined within that router.
router-use.js
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```
// Middleware function for the router
const routerMiddleware = (req, res, next) => {
  console.log('Middleware for the router');
  next();
};

// Apply middleware to the router
router.use(routerMiddleware);
```
Mounting the Router:

Once routes and middleware are defined within the Router, it needs to be mounted on the main Express application. This is done using the app.use() method.
mounting-router.js
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```
// Mount the router on the main app
app.use('/api', router);
```
In this example, all routes defined in the Router will be prefixed with /api.

🚀 Advanced Features

Nested Routers:

Routers can be nested within each other, allowing for even more modularization. This is particularly useful for breaking down complex applications into smaller, manageable components.
nested-routers.js
Copied
```
const nestedRouter = express.Router();

nestedRouter.get('/example', (req, res) => {
  res.send('Nested router example');
});

router.use('/nested', nestedRouter);
```
In this example, the nested router is mounted under the /nested path in the main router.

📝 Example

Let's illustrate the usage of the Router with a comprehensive example:

example.js

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

// Middleware function for the router
const routerMiddleware = (req, res, next) => {
  console.log('Middleware for the router');
  next();
};

// Apply middleware to the router
router.use(routerMiddleware);

// Define a route using the Router
router.get('/users', (req, res) => {
  res.send('List of users');
});

// Mount the router on the main app
app.use('/api', router);

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

In this example, a simple Router is defined with a middleware and a route. The router is then mounted on the main application under the /api path.

🎉 Conclusion

In conclusion, the Router in Express.js is a powerful tool for organizing and modularizing route handling in your applications. It provides a structured way to group related routes and middleware, enhancing code organization and maintainability.

This overview has covered the basic structure, key methods, and advanced features of the Router, empowering you to efficiently manage routes in your Express.js applications.