Step 2: The first route

const http = require("http");

const todos = [];
let nextId = 1;

function send(res, status, data) {
  res.writeHead(status, { "Content-Type": "application/json" });
  res.end(JSON.stringify(data));
}

function handle(req, res) {
  if (req.method === "GET" && req.url === "/todos") return send(res, 200, todos);
  send(res, 404, { error: "Not found" });
}

// ---- demo: start on a free port, make a few requests, stop ----
const server = http.createServer(handle);
server.listen(0, async () => {
  const base = `http://localhost:${server.address().port}`;
  const call = async (method, path, body) => {
    const res = await fetch(base + path, { method, body: body ? JSON.stringify(body) : undefined });
    const text = await res.text();
    console.log(method, path, "->", res.status, text || "(empty)");
  };
  await call("GET", "/todos");
  await call("GET", "/nothing-here");
  server.close();
});

GET /todos -> 200 []
GET /nothing-here -> 404 {"error":"Not found"}