Create HTTP Web Server in Node.js

Node.js has a built-in http module for creating servers. In practice, most projects use Express instead, but understanding the bare http module helps you see what Express is doing underneath.

Creating a server

Import the http module and call http.createServer(). It takes a callback that runs on every request.

const http = require('http');

const server = http.createServer((req, res) => {
  console.log('request received');
});

Then tell the server to start listening:

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

The response object

To send a response, set a header describing the content type, write the body, and end the response.

Plain text:

const http = require('http');

const server = http.createServer((req, res) => {
  res.setHeader('Content-Type', 'text/plain');
  res.write('Hello, world');
  res.end();
});

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

HTML:

const http = require('http');

const server = http.createServer((req, res) => {
  res.setHeader('Content-Type', 'text/html');
  res.write('<p>Hello, world</p>');
  res.write('<p>Hello, again</p>');
  res.end();
});

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

Serving HTML files

Use the fs module to read an HTML file and send it as the response.

const http = require('http');
const fs = require('fs');

const server = http.createServer((req, res) => {
  res.setHeader('Content-Type', 'text/html');

  fs.readFile('./views/index.html', (err, data) => {
    if (err) {
      console.log(err);
      res.end();
    } else {
      res.end(data);
    }
  });
});

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

Basic routing

Use a switch statement on req.url to serve different pages.

const http = require('http');
const fs = require('fs');

const server = http.createServer((req, res) => {
  res.setHeader('Content-Type', 'text/html');

  let filePath = './views/';
  switch (req.url) {
    case '/':
      filePath += 'index.html';
      res.statusCode = 200;
      break;
    case '/about':
      filePath += 'about.html';
      res.statusCode = 200;
      break;
    default:
      filePath += '404.html';
      res.statusCode = 404;
  }

  fs.readFile(filePath, (err, data) => {
    if (err) {
      console.log(err);
      res.end();
    }
    res.end(data);
  });
});

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

Status codes

The status code describes the type of response. Set it with res.statusCode:

Range	Meaning
100s	Informational
200s	Success
300s	Redirects
400s	Client errors
500s	Server errors

Common codes: 200 (OK), 301 (Moved Permanently), 404 (Not Found), 500 (Internal Server Error).

Redirects

Use setHeader('Location', ...) with a 301 status to redirect a request:

case '/about-us':
  res.statusCode = 301;
  res.setHeader('Location', '/about');
  res.end();
  break;

Next steps

For real web apps and APIs, use Express . It handles routing, middleware, and JSON responses with far less boilerplate than the raw http module.