gistfile1.txt

// Do this

const { writable, readable } = new TransformStream();

const writer = writable.getWriter();
writer.write('something');
writer.write('something');
writer.write('something');

// Here, you can use the writer's `.ready` promise to determine
// when backpressure has been relieved.

gistfile2.txt

// Or this... (less desirable)

let writable;
const readable = new ReadableStream({
  start(c) {
    writable = new WritableStream({
      write(chunk) {
        c.enqueue(chunk);
      }
    }, {
      highWaterMark: c.desiredSize
    );
  }
});

readablecontroller.js

// Bad... don't do this

let controller;
const readable = new ReadableStream({
  start(c) { controller = c }
});

c.enqueue('something');
c.enqueue('something');
c.enqueue('something'); // etc