playlist-extension/content_scripts/content.js

(function () {
  console.log("HELLO FROM PLAYLIST!", Math.floor(Math.random() * 999));

  function msgPlayEvt(type, target) {
    const payload = {
      type,
      url: PlaylistUtils.cleanVideoUrl(window.location.href),
      timestamp: target.currentTime,
      duration: target.duration,
      title: document.title.replace(/ - YouTube$/, ""),
    };
    return browser.runtime.sendMessage(payload);
  }

  // YouTube is a SPA: advancing to the next video in a queue swaps in a new
  // <video> element without a full page load, so a listener attached to one
  // specific element (grabbed once at injection time) stops receiving events.
  // Listening on `document` in the capture phase catches every video, past or
  // future, while `#movie_player` scopes this to the standard watch-page
  // player only (excludes home/search hover-preview thumbnails, Shorts, etc).
  ["play", "playing", "pause", "ended"].forEach(function (type) {
    document.addEventListener(
      type,
      function (evt) {
        if (
          evt.target.tagName === "VIDEO" &&
          evt.target.closest("#movie_player")
        ) {
          msgPlayEvt(type, evt.target);
        }
      },
      true,
    );
  });

  function playIt(tryAgain) {
    const video = document.querySelector("video");
    const smallPlay = document.querySelector(
      'button.ytp-play-button.ytp-button[data-title-no-tooltip="Play"]',
    );
    const bigPlay = document.querySelector(
      "button.ytp-large-play-button.ytp-button",
    );

    if (video && video.paused && smallPlay && bigPlay) {
      bigPlay.click();
    }

    if ((!video || (video && video.paused)) && tryAgain > 0) {
      setTimeout(playIt, 500, tryAgain - 1);
    }
  }

  // Listen for messages from the popup or background script
  browser.runtime.onMessage.addListener((message) => {
    if (message.type === "print") {
      console.log("MESSAGE", message);
    }
    if (message.type === "autoplay") {
      setTimeout(playIt, 100, 10);
    }
  });
})();