Open channels with updates in new tabs, to be launched from Tampermonkey context menu

youtube-check-out-updated-channels.js

// ==UserScript==
// @name         YouTube Check Out Updated Channels
// @namespace    http://tampermonkey.net/
// @version      0.5
// @description  Open channels with updates in new tabs
// @author       Nathaniel Wu
// @include      *www.youtube.com/*
// @license      Apache-2.0
// @supportURL   https://gist.github.com/Nathaniel-Wu/fabd62df2d6146121fa4b9cfcae08763
// @run-at       context-menu
// ==/UserScript==

(function () {
    'use strict';

    function is_channel_updated(channel) {
        return window.getComputedStyle(channel.querySelector('div#newness-dot')).display == "block";
    }
    function check_for_updates(subscriptions) {
        subscriptions.querySelectorAll('ytd-guide-entry-renderer').forEach(channel => {
            if (is_channel_updated(channel)) {
                let link = channel.querySelector('a').href;
                if (!Boolean(link.match(/\/videos($|\/$)/)))
                    link += '/videos'
                window.open(link);
            }
        });
    }
    function checkout_updated_channels() {
        let subscriptions = document.querySelector('div#content > tp-yt-app-drawer#guide div#sections > ytd-guide-section-renderer:nth-of-type(2) > div#items');//subject to change
        if (subscriptions == null)
            return false;
        let channels = subscriptions.querySelectorAll(':scope > ytd-guide-entry-renderer');
        if (is_channel_updated(channels[channels.length - 1])) {
            let active_DOMNodeInsertion = 0;
            subscriptions.addEventListener("DOMNodeInserted", () => {
                active_DOMNodeInsertion++;
                setTimeout(() => {
                    active_DOMNodeInsertion--;
                    if (active_DOMNodeInsertion == 0)
                        check_for_updates(subscriptions);
                }, 100);
            });
            subscriptions.querySelector('ytd-guide-collapsible-entry-renderer > ytd-guide-entry-renderer#expander-item').click();
        } else
            check_for_updates(subscriptions);
        return true;
    }
    function repeat_until_successful(function_ptr, interval) {
        if (!function_ptr())
            setTimeout(() => {
                repeat_until_successful(function_ptr, interval);
            }, interval);
    }
    function in_iframe() {
        try {
            return window.self !== window.top;
        } catch (e) {
            return true;
        }
    }
    if (!in_iframe()) {
        repeat_until_successful(checkout_updated_channels, 1000);
    }
})();