Express router.use() Method

Posted in Express Tutorial

Updated on Oct 28, 2024

By Mari Selvan

👁️ 102 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the world of Express.js, the router.use() method plays a crucial role in middleware handling and routing configuration. This versatile method allows you to apply middleware functions to a specific route or across an entire router, enhancing the flexibility and maintainability of your Express applications.

In this guide, we will explore the syntax, use cases, and best practices associated with the router.use() method.

💡 Syntax

The syntax for the router.use() method is as follows:

syntax.js

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router.use([path,] callback [, callback, ...])

path (optional): A string representing the route or path for which the middleware functions are invoked. If omitted, the middleware will be executed for all routes associated with the router.
callback: The middleware function(s) to be executed for the specified route or across the entire router.

❓ How router.use() Works

The router.use() method is used to specify middleware functions that will be executed in the order they are declared when an HTTP request matches the specified route. If no route is provided, the middleware functions will be applied to all routes associated with the router.

example.js

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

// Middleware function for logging all requests
router.use((req, res, next) => {
  console.log(`Request received at ${new Date()}`);
  next();
});

// Your route handlers go here

module.exports = router;

In this example, the middleware function logs information for all requests reaching the router.

📚 Use Cases

Logging:

Use router.use() to implement logging for specific routes or across the entire router, providing insights into request patterns.
example.js
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```
router.use((req, res, next) => {
  console.log(`Request received at ${new Date()}`);
  next();
});
```

Authentication Middleware:

Secure specific routes or a group of routes by applying authentication middleware using router.use().

example.js

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const authenticateUser = (req, res, next) => {
  // Implement your authentication logic here
  if (req.isAuthenticated()) {
    return next();
  } else {
    res.status(401).send('Unauthorized');
  }
};

// Apply authentication middleware to all routes under '/secure'
router.use('/secure', authenticateUser);

🏆 Best Practices

Order of Declaration:

Ensure the order in which middleware functions are declared, as they will be executed in that order. Place more specific route handlers before generic ones.
Combining Middleware:

Combine multiple middleware functions within a single router.use() declaration for conciseness and organization.
Conditional Application:

Conditionally apply middleware based on specific criteria, enhancing flexibility in your application's behavior.

🎉 Conclusion

The router.use() method in Express.js is a powerful tool for handling middleware functions within a router. Whether you're implementing logging, authentication, or other cross-cutting concerns, understanding how to leverage router.use() will help you create more modular and maintainable Express applications.

Now, equipped with knowledge about the router.use() method, enhance your Express.js projects with organized and efficient middleware handling!