Automatically adjust YouTube playback speed based on video type (music vs normal)

YouTube Auto Speed Adjuster.js

// ==UserScript==
// @name         YouTube Auto Speed Adjuster
// @namespace    https://github.com/f13end
// @version      1.0
// @description  Automatically adjust YouTube playback speed based on video type (music vs normal)
// @author       F13END
// @homepageURL  https://github.com/f13end
// @match        https://www.youtube.com/*
// @grant        none
// ==/UserScript==

(function () {
    'use strict';

    const NORMAL_SPEED = 2.0;   
    const MUSIC_SPEED = 1.0;    

    const MUSIC_KEYWORDS = [
        "official music video",
        "official video",
        "lyrics",
        "song",
        "mix",
        "audio",
        "remix",
        "album",
        "Dj",
        "single",
        "music",
        "track"
    ];

    function isMusicVideo(title, channel) {
        const lowerTitle = (title || "").toLowerCase();
        const lowerChannel = (channel || "").toLowerCase();
        if (MUSIC_KEYWORDS.some(keyword => lowerTitle.includes(keyword))) return true;
        if (lowerChannel.includes("music")) return true;
        return false;
    }

    function setPlaybackSpeed(video, speed) {
        if (video && Math.abs(video.playbackRate - speed) > 0.001) {
            video.playbackRate = speed;
            console.log(`YouTube Auto Speed (f13end): ${speed}x applied`);
        }
    }

    function getTitleElement() {
        return document.querySelector('h1.title yt-formatted-string') || document.querySelector('#container h1');
    }

    function getChannelElement() {
        return document.querySelector('#meta-contents ytd-channel-name a') || document.querySelector('#text-container yt-formatted-string');
    }

    function checkAndSetSpeed() {
        const video = document.querySelector('video');
        const titleEl = getTitleElement();
        const channelEl = getChannelElement();

        if (!video) return;

        const title = titleEl ? (titleEl.textContent || "") : "";
        const channel = channelEl ? (channelEl.textContent || "") : "";

        const speed = isMusicVideo(title, channel) ? MUSIC_SPEED : NORMAL_SPEED;
        setPlaybackSpeed(video, speed);
    }

    let lastUrl = location.href;
    const urlObserver = new MutationObserver(() => {
        const currentUrl = location.href;
        if (currentUrl !== lastUrl) {
            lastUrl = currentUrl;
            setTimeout(checkAndSetSpeed, 1200);
            setTimeout(checkAndSetSpeed, 2400);
            setTimeout(checkAndSetSpeed, 4000);
        }
    });
    urlObserver.observe(document.body, { childList: true, subtree: true });

    const videoListObserver = new MutationObserver(() => checkAndSetSpeed());
    videoListObserver.observe(document, { childList: true, subtree: true });

    window.addEventListener('load', () => setTimeout(checkAndSetSpeed, 1000));
    window.addEventListener('yt-navigate-finish', () => setTimeout(checkAndSetSpeed, 1000));
})();