油猴脚本自动开启 YouTube 中文字幕

// ==UserScript==
// @name        YouTube 自动设置中文字幕
// @match       *://youtube.com/*
// @match       *://*.youtube.com/*
// @author      kernelpanic
// @description 自动设置中文字幕，如果没有则自动选择英文->简体中文翻译
// @icon        https://www.youtube.com/favicon.ico
// @noframes
// @run-at      document-idle
// @version     1.0
// ==/UserScript==

(() => {
  let main = function(event) {
      if (event !== undefined && event.target.numNavigations_ == 0) {
          return;
      }

      if (!/\/(watch)/.test(window.location.pathname)) {
          return;
      }

      let player = document.querySelector('.html5-video-player');

      player.toggleSubtitles();

      var trackList = player.getOption('captions', 'tracklist');

      if (trackList === undefined) {
         console.log('本视频不支持字幕或翻译！');
          return;
      }

      var availableTracks = trackList.map(track => track.languageCode);
      console.log(`支持的字幕: ${availableTracks}`)

      if(availableTracks.includes('zh-Hans')){
          console.log('有中文字幕，直接加载！');
          player.setOption('captions', 'track', {languageCode: 'zh-Hans'});
      }else{
          console.log('没有中文字幕，设置自动翻译');
          player.setOption('captions', 'track', {"languageCode":"en","languageName":"英语","displayName":"英语","kind":"","name":null,"id":null,"is_servable":false,"is_default":false,"is_translateable":true,"vss_id":".en","translationLanguage":{"languageCode":"zh-Hans","languageName":"中文（简体）"}});
      }
  }
  window.addEventListener('yt-navigate-finish', main);
})();