youtube-subtitle.js

youtube-subtitle.js

(async () => {
  const wait = (ms) => new Promise(resolve => setTimeout(resolve, ms));

  const subtitleButton = document.querySelector('.ytp-subtitles-button');
  if (!subtitleButton) {
    return;
  }
  const subtitleButtonState = subtitleButton.getAttribute('aria-pressed') === 'true';
  subtitleButton.click();
  if (subtitleButtonState) {
    return;
  }

  const settingButton = document.querySelector('.ytp-settings-button');
  if (!settingButton) {
    return;
  }
  settingButton.click();

  await wait(250);

  const subtitleMenuItem = document.querySelector('.ytp-settings-menu .ytp-menuitem-label-count');
  if (!subtitleMenuItem) {
    return;
  }
  subtitleMenuItem.click();

  await wait(250);
  
  const subtitleListNodes = document.querySelectorAll('.ytp-settings-menu .ytp-menuitem-label');
  const subtitles = Array.from(subtitleListNodes).map(_ => _.innerText);
  const japaneseSubtitleIndex = subtitles.findIndex(_ => _ === '日本語');
  if (japaneseSubtitleIndex !== -1) {
    subtitleListNodes[japaneseSubtitleIndex].click();
    return;
  }

  const machineTranslateSubtitleIndex = subtitles.findIndex(_ => _ === '自動翻訳');
  if (machineTranslateSubtitleIndex!== -1) {
    subtitleListNodes[machineTranslateSubtitleIndex].click();
  }

  await wait(250);

  const machineTranslateSubtitleListNodes = document.querySelectorAll('.ytp-settings-menu .ytp-menuitem-label');
  const machineTranslateSubtitles = Array.from(machineTranslateSubtitleListNodes).map(_ => _.innerText);
  const machineTranslateJapaneseSubtitleIndex = machineTranslateSubtitles.findIndex(_ => _ === '日本語');
  if (machineTranslateJapaneseSubtitleIndex !== -1) {
    machineTranslateSubtitleListNodes[machineTranslateJapaneseSubtitleIndex].click();
  }
})();