Learning Node.js - Building a Simple HTTP Server with http

#Introduction

Everything you've learned so far — core modules, the event loop, file I/O — finds its main stage here: the HTTP server. Node.js provides the http module, which lets you serve HTTP responses with just a few lines of code, without any framework.

Episode 7 builds your first HTTP server from scratch: createServer, how to read the method and URL from a request, how to send a response with the right status codes and headers, and how to test it all with curl. This is the foundation that Express will use directly in episode 9.

#Building Your First HTTP Server

#createServer and listen

An HTTP server in Node.js is built from a single handler function called for every request. The http module returns a server from createServer, and then the server is activated with listen:

First HTTP server

import http from "node:http";
 
const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader("Content-Type", "text/plain; charset=utf-8");
  res.end("Halo dari Node.js");
});
 
server.listen(3000, () => {
  console.log("Server berjalan di http://localhost:3000");
});

Run it with node server.js, then open http://localhost:3000 in the browser. The handler function receives req (request) and res (response), res.statusCode sets the status code, setHeader sets the header, and res.end sends the response body.

#Reading the Request: Method and URL

#Using Data from the Client

A good server must know what's being asked for. The req object holds two of the most important properties: method and url:

Read the method and url

import http from "node:http";
 
const server = http.createServer((req, res) => {
  console.log(req.method, req.url);
  res.end("Method: " + req.method + ", URL: " + req.url);
});
 
server.listen(3000);

On every incoming request, console.log(req.method, req.url) records the method like GET or POST along with the path like /halaman. This is the raw material for building routing — we'll build a complete router in episode 8.

#Sending the Response: Status and Headers

#The Right Status Codes

Status codes tell the client the result of a request. Some of the most commonly used:

• 200: success.
• 201: resource successfully created.
• 301: permanent redirect.
• 400: invalid request.
• 401: not authenticated.
• 404: resource not found.
• 500: server-side error.

Response with different statuses

import http from "node:http";
 
const server = http.createServer((req, res) => {
  if (req.url === "/") {
    res.writeHead(200, { "Content-Type": "text/html" });
    res.end("<h1>Beranda</h1>");
  } else {
    res.writeHead(404, { "Content-Type": "text/plain" });
    res.end("Halaman tidak ditemukan");
  }
});
 
server.listen(3000);

Notice res.writeHead(404, {...}), which sets the status code and headers at once. The combination of correct status with the matching Content-Type header is a hallmark of a good API.

#Testing the Server with curl

#Verifying from the Terminal

curl is a backend developer's best friend. Test your server from the terminal:

curl http://localhost:3000/
curl -i http://localhost:3000/tidak-ada

curl -i http://localhost:3000/tidak-ada shows the status line and headers along with the body — the fastest way to see whether your response is correct. For a running server, we'll use curl intensively in episodes 8 through 10 to test APIs.

#The Server Process and Graceful Shutdown

A server runs endlessly waiting for requests. To stop it, press Ctrl+C in the terminal. In production, you need to handle shutdown signals gracefully — cleaning up database connections before exiting — which we'll discuss in depth in episode 22.

#Closing

Here's what to take away:

• http.createServer creates a server with a single handler function.
• server.listen(port) activates the server on a given port.
• req.method and req.url are the raw material for routing.
• res.writeHead sets the status code and headers at once.
• Status codes 2xx are success, 4xx are client errors, 5xx are server errors.
• curl -i shows the status line, headers, and body for quick testing.

In the next episode, episode 8, we'll discuss routing, middleware, and request/response — building a manual router, parsing query strings, the middleware pattern with a next function, and reading the request body. After this, you can build a multi-route API with pure Node.js.