A beginner HTTP server in Deno

deno_beginner_http_server.ts

import { serve } from "https://deno.land/std/http/mod.ts";

async function reqHandler(req: Request) {
  if (
    !req.headers.has("Authorization") ||
    req.headers.get("Authorization")?.split(" ")[1] !==
      Deno.env.get("AUTH_TOKEN")
  ) {
    return new Response(null, { status: 401 });
  }
  if (req.method !== "POST") {
    return new Response(null, { status: 405 });
  }
  const { pathname: path, searchParams: query } = new URL(req.url);
  if (path !== "/users/search") {
    return new Response(null, { status: 404 });
  }
  let userId;
  if (
    req.headers.has("content-type") &&
    req.headers.get("content-type")?.startsWith("application/json") &&
    req.body
  ) {
    userId = (await req.json()).userId;
  }
  if (!userId) {
    userId = query.get("userId");
  }
  if (!userId) {
    return new Response(null, { status: 400 });
  }
  const userObj = JSON.parse(await Deno.readTextFile("./db.json"))[userId];
  if (!userObj) {
    return new Response(null, { status: 204 });
  }
  return new Response(JSON.stringify(userObj), {
    headers: {
      "content-type": "application/json; charset=UTF-8",
    },
  });
});

serve(reqHandler, { port: 5000 });