fetch('https://html.spec.whatwg.org').then(response => {

  const reader = response.body.getReader();

  const decoder = new TextDecoder();

  reader.read().then(function process(result) {

    if (result.done) return;

    const text = decoder.decode(result.value, {stream: true});

    console.log(text);

    return reader.read().then(process);

  }).then(() => {

    console.log('All done!');

  });

});