7. How to Use Custom Request Handlers in a Node.js Server

Setting up custom request handlers in a Node.js server is an important part of building web applications. This allows developers to control how their server responds to different requests. Node.js is widely used and helps power many web apps today.

Basic Ideas

Node.js uses a built-in part called the http module. This module helps create servers and manage the incoming requests. When a request arrives, a request handler processes it and decides what response to send back.

Creating a Simple Server

Here’s a simple example of how to create a server:

const http = require('http');

const server = http.createServer((req, res) => {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Hello World\n');
});

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

This piece of code makes a server that listens on port 3000 and replies with "Hello World" to anyone who sends a request.

Custom Request Handlers

Custom request handlers let you set up different responses based on the URL or type of request. You can use a few different ways to create these handlers.

1. Using Path-Based Routing

You can write handlers for different web pages using simple if statements:

const handler = (req, res) => {
    if (req.url === '/about' && req.method === 'GET') {
        res.writeHead(200, { 'Content-Type': 'text/html' });
        res.end('<h1>About Page</h1>');
    } else if (req.url === '/contact' && req.method === 'GET') {
        res.writeHead(200, { 'Content-Type': 'text/html' });
        res.end('<h1>Contact Page</h1>');
    } else {
        res.writeHead(404, { 'Content-Type': 'text/plain' });
        res.end('404 Not Found');
    }
};

2. Using a Routing Library

For bigger apps, it’s easier to use a library like Express.js, which can help organize your routes better:

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

app.get('/about', (req, res) => {
    res.send('<h1>About Page</h1>');
});

app.get('/contact', (req, res) => {
    res.send('<h1>Contact Page</h1>');
});

// 404 handling
app.use((req, res) => {
    res.status(404).send('404 Not Found');
});

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

3. Handling Errors

It's very important to handle errors well. Here’s how you can manage errors in Express:

app.use((err, req, res, next) => {
    console.error(err.stack);
    res.status(500).send('Something broke!');
});

Performance Information

Node.js is super powerful! It can handle around 1 million connections at the same time with just one core. This is much better than many older server setups. In fact, 33% of developers like using Node.js to create RESTful APIs because it's lightweight and works very efficiently.

Conclusion

To sum up, you can create custom request handlers in a Node.js server using simple if statements or with the help of libraries like Express.js. Node.js is great for working with many requests at once, making it a top choice for building fast web applications. Good error handling and organized routing can make your applications even better.