infinite_text_stream.html

<script>
const readableStream = new ReadableStream({
  pull(ctrl) {
    // "ABCDE\n"
    ctrl.enqueue(new Uint8Array([65, 66, 67, 68, 69, 10]));
  }
});

fetch("https://ppng.io/mytext", {
  method: 'POST',
  body: readableStream,
  allowHTTP1ForStreamingUpload: true,
});
</script>