yt-open-transcript.js

javascript: (async () => {
  const TOP = window.opener || window.top;
  const document = TOP.document;

  function nextFrame() {
    return new Promise(done => {
      requestAnimationFrame(done);
    });
  }

  const clickOpenTranscript = () =>
    [...document.querySelectorAll("ytd-menu-service-item-renderer")]
      .filter(it => it.textContent.includes("Open transcript"))
      .map(b => b.click()).length > 0;

  const clickOpenMenu = () =>
    [...document.querySelectorAll('[aria-label="More actions"]')].forEach(b =>
      b.click()
    );

  async function turnOnTranscript() {
    if (!clickOpenTranscript()) {
      clickOpenMenu();
      await nextFrame();
      clickOpenTranscript();
    }
  }

  try {
    await turnOnTranscript();
  } catch (e) {
    console.error(e);
  }
})();