Using trumpet to read/modify/write the IncomingMessage stream in @hapi/h2o2

index.js

const Hapi = require("@hapi/hapi");
const H2o2 = require("@hapi/h2o2");
const { PassThrough } = require("stream");
const trumpet = require("trumpet");

const start = async function () {
  const server = Hapi.server({
    host: "localhost",
    port: 8000,
  });
  try {
    await server.register(H2o2);

    server.route({
      method: "GET",
      path: "/",
      handler: async (request, h) => {
        return h.proxy({
          uri: "https://hapi.dev",
          onResponse: async function (err, res, request, h, settings, ttl) {
            const tr = trumpet();
            const ws = tr.select("a.index-button").createWriteStream();
            ws.end("Make me hapi");

            const response = h
              .response(res.pipe(tr).pipe(new PassThrough()))
              .ttl(ttl)
              .code(res.statusCode)
              .passThrough(!!settings.passThrough);

            response.headers = res.headers;
            return response;
          },
        });
      },
    });

    server.start();

    console.log(`Server started at:  ${server.info.uri}`);
  } catch (e) {
    console.log("Failed to load h2o2");
  }
};

start();

Because trumpet is returning an old-style Node.js stream you can convert via a PassThrough() which is an in/out Transform to a new-style stream.