youtubeLiveObserver.user.js

// ==UserScript==
// @name          Auto Refresh YouTube Live
// @description   Automatically tracks live head for YouTube Live
// @match         https://www.youtube.com/*
// @version       1.0.3
// @homepageURL   https://gist.github.com/kyohsuke/eac69ddef61d4cd8d165c8b2e59ff0ef
// @updateURL     https://gist.githubusercontent.com/kyohsuke/eac69ddef61d4cd8d165c8b2e59ff0ef/raw/youtubeLiveObserver.user.js
// @downloadURL   https://gist.githubusercontent.com/kyohsuke/eac69ddef61d4cd8d165c8b2e59ff0ef/raw/youtubeLiveObserver.user.js
// @icon          https://cdn3.iconfinder.com/data/icons/social-network-30/512/social-06-1024.png
// @grant         none
// ==/UserScript==

(function(){
  function liveTracker() {
    console.log("Init Live Tracker");

    const initialInterval = 3;

    let observer = null;
    let liveInterval = initialInterval;
    let currentURL = "";

    function isLive() {
      let liveBtn = document.getElementsByClassName("ytp-live-badge")[0];
      return (liveBtn != undefined && window.getComputedStyle(liveBtn).display != "none");
    }

    function addObserver() {
      let liveBtn = document.getElementsByClassName("ytp-live-badge")[0];
      const handleMutation = (mutationsList, observer) => {
        mutationsList.forEach(mutation => {
          // 変更に対する処理
          let onLive = false;
          mutation.target.classList.forEach(className => {
            if(className == "ytp-live-badge-is-livehead") {
              onLive = true;
            }
          });

          if(isLive() && !onLive) {
            let nextDelay = 1000 * liveInterval;
            console.log("Move ahead after", liveInterval, "seconds");

            if(liveInterval < 10) {
              liveInterval += 1;
            }

            setTimeout(function(){
              if(isLive()) {
                console.log("Click Live!");
                liveBtn.click();
              }
            }, nextDelay);
          }
        });
      };

      if(observer != null) {
        observer.disconnect();
      }

      observer = new MutationObserver(handleMutation);
      observer.observe(liveBtn, {
        attributeFilter: ["class"],
      });
    }

    function putEvents() {
      liveInterval = initialInterval;
      addObserver();
    }

    setInterval(function(){
      let pickURL = location.href;
      if(currentURL != pickURL) {
        currentURL = pickURL;
        setTimeout(putEvents, 1000);
      }
    }, 1000);
  }

  liveTracker();
})();