Routing in Express.js

1. Introduction

Routing in Express.js is a way to define the endpoints (URLs) of your web application and associate them with specific request handlers. This enables you to build RESTful APIs and web applications efficiently.

2. Routing Basics

In Express.js, the routing mechanism allows you to handle different HTTP requests to different endpoints. You can define routes using the app.get(), app.post(), app.put(), and app.delete() methods.

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

app.get('/', (req, res) => {
    res.send('Welcome to Express.js!');
});

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

3. HTTP Methods

Express.js supports various HTTP methods which correspond to the CRUD operations:

• GET - Retrieve data
• POST - Create new data
• PUT - Update existing data
• DELETE - Remove data

4. Route Parameters

Route parameters allow you to capture values from the URL. You can define a route with a parameter by prefixing it with a colon.

app.get('/user/:id', (req, res) => {
    const userId = req.params.id;
    res.send(`User ID: ${userId}`);
});
        

5. Middleware Functions

Middleware functions are functions that have access to the request object, response object, and the next middleware function. Middleware can modify the request and response objects, end the request-response cycle, or call the next middleware function.

const logger = (req, res, next) => {
    console.log(`${req.method} ${req.url}`);
    next();
};

app.use(logger);
        

6. Best Practices

When working with routing in Express.js, consider the following best practices:

• Organize routes in separate files for better maintainability.
• Use descriptive route names.
• Implement error handling middleware.
• Validate input data to ensure security.

7. FAQs