function json(statusCode, obj) {

  return {

    statusCode,

    headers: { "content-type": "application/json" },

    body: JSON.stringify(obj)

  };

}

​

async function handler(event) {

  const path = event.path || "/";

  const method = (event.httpMethod || "GET").toUpperCase();

​

  if (method === "GET" && path === "/health") {

    return json(200, { ok: true });

  }

​

  if (method === "POST" && path === "/echo") {

    const body = typeof event.body === "string" ? event.body : JSON.stringify(event.body || {});

    return json(200, { youSent: body });

  }

​

  return json(404, { error: "not found", path, method });

}

​

if (require.main === module) {

  (async () => {

    console.log(await handler({ path: "/health", httpMethod: "GET" }));

    console.log(await handler({ path: "/echo", httpMethod: "POST", body: { a: 1 } }));

  })();