サーバー

import http from "http";

type Handler = (
  req: http.IncomingMessage,
  res: http.ServerResponse,
  url: URL
) => void | Promise<void>;

const routes = new Map<string, Handler>([
  ["GET /", homeHandler],
  ["GET /users", getUsersHandler],
  ["POST /users", createUserHandler],
]);

const server = http.createServer(async (req, res) => {
  const method = req.method ?? "GET";

  const url = new URL(
    req.url ?? "/",
    `http://${req.headers.host}`
  );

  const key = `${method} ${url.pathname}`;

  const handler = routes.get(key);

  if (!handler) {
    res.writeHead(404);
    res.end("Not Found");
    return;
  }

  await handler(req, res, url);
});