Node.js Fundamentals - HTTP Module

HTTP Module

The HTTP module is a built-in Node.js tool for creating web servers and making web requests. It’s basic and low-level and also great for learning, but for real apps, use frameworks like Express.js. Import it with import http from "http".

Key Concepts

Server: Listens for requests on a port (e.g., 3000).
Request (req): Incoming data fom client (URL, method like GET/POST).
Response (res): What you send back (HTML, JSON, status codes).
Methods: GET (fetch data), POST (send data), etc.
Ports: Common is 3000 for local dev.

Common Commands

Include import http from "http;" at the top.

Create a Basic Server:

const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' })
  res.end('Hello from Node.js server!')
})
 
server.listen(3000, () => {
  console.log('Server running at http://localhost:3000')
})

Explanation: Creates a server which you can visit at http://localhost:3000 in browser to see message. 200 is success status.

Handle Different Routes (Basic routing):

// inside the createServer callback
if (req.url === '/') {
  res.end('Home Page')
} else if (req.url === '/about') {
  res.end('About Page')
} else {
  res.writeHead(404)
  res.end('Not found')
}

Explanation: Responds based on URL path.

Handle POST Request (e.g., form data):

// inside the createServer callback
if (req.method === 'POST' && req.url === '/submit') {
  let body = ''
  req.on('data', (chunk) => (body += chunk))
  req.on('end', () => {
    console.log(body)
    res.end('Data received')
  })
}

Explanation: Collects data sent via POST.