echo_debug_sever.ts

// debug server
import http from "http";
import { URL } from "url";
import { inspect } from "util";

const readBody = (req: http.IncomingMessage) =>
  new Promise<Buffer>((resolve, reject) => {
    const chunks: Buffer[] = [];
    req.on("data", (chunk) => chunks.push(chunk));
    req.on("end", () => resolve(Buffer.concat(chunks)));
    req.on("error", reject);
  });

http
  .createServer(async (req, res) => {
    const url = new URL(req.url!, "http://localhost");
    const { hostname, pathname, searchParams } = url;
    const { method, headers } = req;
    const body = await readBody(req);
    const bodyStr = body.toString();
    const bodyStrTruncated =
      bodyStr.length > 100 ? bodyStr.slice(0, 100) + "..." : bodyStr;
    console.log(
      `${method} ${hostname}${pathname}${searchParams} ${inspect(
        headers
      )} ${bodyStrTruncated}`
    );
    res.writeHead(200, { "Content-Type": "text/plain" });
    res.end(body);
  })
  .listen(3000);