Stop YouTube Channel Featured Video Autoplay (TamperMonkey/Greasemonkey)

stop_youtube_channel_autoplay.js

// ==UserScript==
// @name         Stop YouTube Channel Autoplay
// @namespace    https://github.com/gregilo
// @version      0.2
// @description  Stop featured videos from autoplaying on YouTube Channel landing pages
// @author       gregilo
// @match        https://www.youtube.com/channel*
// @match        https://www.youtube.com/user*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    /**
     * Poll for a given set of acceptance criteria with timeout (thank you David Walsh!)
     * @param  {function} fn Function containing acceptance criteria
     * @return {object}      Promise that resolves when acceptance criteria is met (rejects on timeout)
     */
    function poll(fn) {
        const endTime = Number(new Date()) + 10000; // timeout after 10 seconds
        const interval = 100; // poll every millisecond

        const checkCondition = function(resolve, reject) {
            // If the condition is met, we're done!
            const result = fn();
            if (result) {
                resolve(result);
            }
            // If the condition isn't met but the timeout hasn't elapsed, go again
            else if (Number(new Date()) < endTime) {
                setTimeout(checkCondition, interval, resolve, reject);
            }
            // Didn't match and too much time, reject!
            else {
                reject(new Error('timed out for ' + fn + ': ' + arguments));
            }
        };

        return new Promise(checkCondition);
    }

    /**
     * Check if video element is loaded on page
     * @return {boolean}
     */
    function detectChannelVideo() {
        let videos = document.getElementsByTagName('video');
        return (videos.length && typeof videos[0] !== 'undefined');
    }

    poll(detectChannelVideo)
        .then(() => {
        console.log('adding event listener')
            let videos = document.getElementsByTagName('video');
            let theVideo = videos[0];
            theVideo.addEventListener('loadeddata', () => theVideo.pause());
        })
        .catch(err => console.error(err));
})();