Node.js Fundamentals

Chapter 6: Creating a Basic Server

6.1 HTTP Server

Node.js http module allows you to create HTTP servers. This is the foundation of web applications.

const http = require('http');

// Create HTTP server
const server = http.createServer((req, res) => {
    // Set response headers
    res.writeHead(200, { 
        'Content-Type': 'text/plain',
        'X-Custom-Header': 'MyValue'
    });
    
    // Send response
    res.end('Hello World');
});

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

Request Object (req):

• req.method: HTTP method (GET, POST, etc.)
• req.url: Request URL path
• req.headers: Request headers
• req.on('data'): Receive request body data

Response Object (res):

• res.writeHead(): Set status code and headers
• res.write(): Write response data
• res.end(): End response
• res.statusCode: Set status code

6.2 Handling Different Routes

Route requests to different handlers based on URL and method.

const http = require('http');

const server = http.createServer((req, res) => {
    const { method, url } = req;
    
    if (method === 'GET' && url === '/') {
        res.writeHead(200, { 'Content-Type': 'text/html' });
        res.end('<h1>Home Page</h1>');
    } else if (method === 'GET' && url === '/about') {
        res.writeHead(200, { 'Content-Type': 'text/html' });
        res.end('<h1>About Page</h1>');
    } else if (method === 'GET' && url === '/api/users') {
        res.writeHead(200, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify([{ id: 1, name: 'John' }]));
    } else {
        res.writeHead(404, { 'Content-Type': 'text/html' });
        res.end('<h1>404 Not Found</h1>');
    }
});

server.listen(3000);

6.3 Handling POST Requests

Process POST requests and read request body data.

const http = require('http');

const server = http.createServer((req, res) => {
    if (req.method === 'POST' && req.url === '/api/users') {
        let body = ';
        
        // Collect request data
        req.on('data', chunk => {
            body += chunk.toString();
        });
        
        // Process when data is complete
        req.on('end', () => {
            try {
                const data = JSON.parse(body);
                // Process data (save to database, etc.)
                res.writeHead(201, { 'Content-Type': 'application/json' });
                res.end(JSON.stringify({ success: true, data }));
            } catch (err) {
                res.writeHead(400, { 'Content-Type': 'application/json' });
                res.end(JSON.stringify({ error: 'Invalid JSON' }));
            }
        });
    } else {
        res.writeHead(404);
        res.end('Not Found');
    }
});

server.listen(3000);

6.4 Server Best Practices

Follow best practices when creating servers.

• Handle errors gracefully
• Set appropriate status codes
• Set correct Content-Type headers
• Validate request data
• Implement proper error handling
• Use environment variables for port
• Log requests for debugging