Creating an HTTP Server — Node.js Fundamentals

Creating an HTTP server

javascript

const http = require("http");

const server = http.createServer((request, response) => {
  // request — the incoming request object
  console.log(`${request.method} ${request.url}`);

  // Route based on URL
  if (request.url === "/" && request.method === "GET") {
    response.writeHead(200, { "Content-Type": "text/html" });
    response.end("<h1>Hello from Node.js!</h1>");

  } else if (request.url === "/api/status" && request.method === "GET") {
    response.writeHead(200, { "Content-Type": "application/json" });
    response.end(JSON.stringify({ status: "ok", uptime: process.uptime() }));

  } else {
    response.writeHead(404, { "Content-Type": "application/json" });
    response.end(JSON.stringify({ error: "Not found" }));
  }
});

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

ANALOGY

This is exactly what Express does. Express doesn't do magic — it wraps Node's http module and adds routing, middleware, and a nicer API. When you call app.get('/api/users', handler) in Express, it's doing exactly the URL matching and response handling you see above, just with much cleaner syntax.

Parsing request body

javascript

const http = require("http");

const server = http.createServer((req, res) => {
  if (req.url === "/api/users" && req.method === "POST") {
    let body = "";

    // Collect data chunks
    req.on("data", chunk => {
      body += chunk.toString();
    });

    // All chunks received — parse and respond
    req.on("end", () => {
      try {
        const data = JSON.parse(body);
        console.log("Received:", data);

        res.writeHead(201, { "Content-Type": "application/json" });
        res.end(JSON.stringify({ success: true, user: data }));
      } catch {
        res.writeHead(400, { "Content-Type": "application/json" });
        res.end(JSON.stringify({ error: "Invalid JSON" }));
      }
    });
  }
});