w2g Auto English CC 2.0

// ==UserScript==
// @name     Auto-English CC
// @author   Paperlanty
// @version  2021.10
// @grant    none
// @include  https://w2g.tv/*
// ==/UserScript==

// console.log('script');
window.addEventListener('load', function () {
  console.log('auto english CC loaded');
  var element = document.querySelector("#w2g-video");

  var MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver;
  var observer = new MutationObserver(initializeIframeObserver);
  observer.observe(element, {
      childList: true,
    characterData: true
  });

  if (document.querySelector("#w2g-video iframe"))
    setSubtitle();

});

function initializeIframeObserver() {
//   console.log('initializeIframeObserver');
  let iframe = document.querySelector("#w2g-video iframe");

  var MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver;
  var iframeObserver = new MutationObserver(setSubtitle);
  iframeObserver.observe(iframe, {
      attributeFilter: ['src'],
    characterData: true
  });

  setSubtitle();
}

function setSubtitle() {
//     console.log('setSubtitle');
    let iframe = document.querySelector("#w2g-video iframe");
    let englishOption = [];

    setTimeout(function() {
//         console.log('waitForSubtitles');
        var waitForSubtitles = new Promise((resolve, reject) => {
            let timeWas = new Date();
            let wait = setInterval(function() {
                if (contains(iframe.contentWindow.document, '#subtitle_button div.popup_item', 'English').length > 0) {
                    console.log("resolved after", new Date() - timeWas, "ms");
                    clearInterval(wait);
                    englishOption = contains(iframe.contentWindow.document, '#subtitle_button div.popup_item', 'English');
                    englishOption[0].click();
                    console.log('subtitle set');
                    resolve();
                } else if (new Date() - timeWas > 5000) { // Timeout
                    console.log("rejected after", new Date() - timeWas, "ms");
                    clearInterval(wait);
                    reject();
                }
            }, 20); // ms interval per subtitle check
        }, 5000); // ms timeout for checking for subtitles
    }, 1000); // ms delay after video load
}

function contains(doc, selector, text) {
  var elements = doc.querySelectorAll(selector);
  return Array.prototype.filter.call(elements, function(element) {
    return RegExp(text).test(element.textContent);
  });
}