text_stream_with_text_encoder_stream.html

<input id="myinput">

<script>
const readableStream = new ReadableStream({
  start(ctrl) {
    window.myinput.onkeyup = (ev) => {
      if (ev.key === 'Enter') {
        ctrl.enqueue(ev.target.value+'\n');
        ev.target.value = '';
      }
    }
  }
}).pipeThrough(new TextEncoderStream());

fetch("https://ppng.io/mytext", {
  method: 'POST',
  body: readableStream,
  headers: { 'Content-Type': 'text/plain;charset=UTF-8' },
  allowHTTP1ForStreamingUpload: true,
});
</script>