YT Polymer 2016 - Early 2019 script by mason20121981

// ==UserScript==
// @name         YT Polymer 2016 - Early 2019 script
// @version      3.7.0
// @description  Disables all features from YouTube after early 2019.
// @author       Magma_Craft
// @license MIT
// @match        *://www.youtube.com/*
// @namespace    https://greasyfork.org/en/users/933798
// @icon         https://www.youtube.com/favicon.ico
// @run-at       document-start
// @require      https://cdnjs.cloudflare.com/ajax/libs/arrive/2.4.1/arrive.min.js
// @grant        none
// ==/UserScript==

@-moz-document domain("youtube.com")
// Enable strict mode to catch common coding mistakes
"use strict";

// Define the flags to assign to the EXPERIMENT_FLAGS object
const flagsToAssign = {
  kevlar_system_icons: false,
  kevlar_refresh_on_theme_change: false,
  kevlar_watch_cinematics: false,
  kevlar_watch_grid: false,
  kevlar_watch_grid_hide_chips: false,
  kevlar_watch_metadata_refresh_no_old_secondary_data: false,
  enable_channel_page_header_profile_section: false,
  kevlar_modern_sd_v2: false,
  kevlar_watch_comments_panel_button: false,
  smartimation_background: false,
  web_animated_like: false,
  web_animated_like_lazy_load: false,
  web_modern_collections_v2: false,
  web_modern_tabs: false,
  web_modern_typography: false,
  web_enable_youtab: false,
  web_snackbar_ui_refresh: false,
  web_rounded_containers: false,
  web_rounded_thumbnails: false,
  web_watch_rounded_player_large: false,
  // Extra additions to remove the watch grid UI
  web_player_enable_featured_product_banner_exclusives_on_desktop: false,
  kevlar_watch_comments_panel_button: false,
  fill_view_models_on_web_vod: true,
  kevlar_watch_flexy_metadata_height: 136,
  kevlar_watch_max_player_width: 1280,
  live_chat_over_engagement_panels: false,
  live_chat_scaled_height: false,
  live_chat_smaller_min_height: false,
  main_app_controller_extraction_batch_18: false,
  main_app_controller_extraction_batch_19: false,
  no_iframe_for_web_stickiness: false,
  optimal_reading_width_comments_ep: false,
  remove_masthead_channel_banner_on_refresh: false,
  small_avatars_for_comments: false,
  small_avatars_for_comments_ep: false,
  web_watch_compact_comments: false,
  web_watch_compact_comments_header: false,
  web_watch_log_theater_mode: false,
  web_watch_theater_chat: false,
  web_watch_theater_fixed_chat: false,
  wn_grid_max_item_width: 0,
  wn_grid_min_item_width: 0
};

const updateFlags = () => {
  // Check if the EXPERIMENT_FLAGS object exists in the window.yt.config_ property chain
  const expFlags = window?.yt?.config_?.EXPERIMENT_FLAGS;

  // If EXPERIMENT_FLAGS is not found, exit the function
  if (!expFlags) return;

  // Assign the defined flags to the EXPERIMENT_FLAGS object
  Object.assign(expFlags, flagsToAssign);
};

// Create a MutationObserver that calls the updateFlags function when changes occur in the document's subtree
const mutationObserver = new MutationObserver(updateFlags);
mutationObserver.observe(document, { subtree: true, childList: true });

document.getElementsByTagName("html")[0].removeAttribute("system-icons");
document.getElementsByTagName("html")[0].removeAttribute("typography");
document.getElementsByTagName("html")[0].removeAttribute("typography-spacing");
document.getElementsByTagName("html")[0].removeAttribute("darker-dark-theme");
document.getElementsByTagName("html")[0].removeAttribute("darker-dark-theme-deprecate");



// Guide adjustments
// Regex to isolate UCID from your videos item
const VIDEOS_URL_REGEX = /(https:\/\/studio.youtube.com\/channel\/)|(\/videos)/g;

const gfconfig = {
    addTrending: true,
    libraryAsGuideSectionTitle: true,
    libraryFolderIcon: true,
    historyItemSignedOut: true,
    exploreSectionToBestOfYT: true,
    expandSubscriptionsSection: true,
    remove: {
        shorts: true,
        yourVideos: true,
        yourClips: true,
        exploreSectionSignedIn: true,
        librarySignedOut: true,
    }
};

const gfi18n = {
    en: {
        whatToWatch: "What to Watch",
        myChannel: "My channel"
    }
};

/**
 * Get a string from the localization strings.
 *
 * @param {string}   string  Name of string to get
 * @param {string}   hl      Language to use.
 * @param {...array} args    Strings.
 * @returns {string}
 */
function getString(string, hl = "en", ...args) {
    if (!string) return;
    var str;
    if (gfi18n[hl]) {
        if (gfi18n[hl][string]) {
            str = gfi18n[hl][string];
        } else if (gfi18n.en[string]) {
            str = gfi18n.en[string];
        } else {
            return;
        }
    } else {
        if (gfi18n.en[string]) str = gfi18n.en[string];
    }

    for (var i = 0; i < args.length; i++) {
        str = str.replace(/%s/, args[i]);
    }

    return str;
}

/**
 * Is the user signed in?
 *
 * @returns bool
 */
function isSignedIn() {
    return yt.config_.LOGGED_IN ?? false;
}

/**
 *
 * @param {object} sections  Guide sections array.
 * @param {string} icon      Icon type to look for
 */
function getItemByIcon(sections, icon) {
    for (var i = 0; i < sections.length; i++) {
        if (sections[i].guideSectionRenderer?.items) {
            var section = sections[i].guideSectionRenderer.items;
            for (var j = 0; j < section.length; j++) {
                if (section[j].guideEntryRenderer) {
                    if (section[j].guideEntryRenderer?.icon?.iconType == icon) {
                        return section[j];
                    }
                } else if (section[j]?.guideCollapsibleSectionEntryRenderer?.sectionItems) {
                    var colsection = section[j].guideCollapsibleSectionEntryRenderer.sectionItems;
                    for (var k = 0; k < colsection.length; k++) {
                        if (colsection[k].guideEntryRenderer) {
                            if (colsection[k].guideEntryRenderer?.icon?.iconType == icon) {
                                return colsection[k];
                            }
                        }
                    }
                }
            }
        }
    }
    return "Could not find item";
}

/**
 * Force Polymer to refresh data of an element.
 *
 * @param {Node} element  Element to refresh data of.
 */
function refreshData(element) {
    var clone = element.cloneNode();
    clone.data = element.data;
    // Let the script know we left our mark
    // in a way that doesn't rely on classes
    // because Polymer likes to cast comments
    // into the void for later reuse
    clone.data.fixedByGF = true;
    for (var i in element.properties) {
        clone[i] = element[i];
    }
    element.insertAdjacentElement("afterend", clone);
    element.remove();
}

/**
 * Modify the guide.
 *
 * @param {Node} guide  ytd-guide-renderer
 * @returns object
 */
function modifyGuide(guide) {
    if (gfconfig.remove.guideFooter) {
        waitForElm("#footer.ytd-guide-renderer").then((elm) => {
            elm.remove();
        });
    }

    var sections = guide.data.items;

    var mainSection = sections[0].guideSectionRenderer.items;
    for (var i = 0; i < mainSection.length; i++) {
        if (mainSection[i].guideEntryRenderer) {
            var item = mainSection[i].guideEntryRenderer;

            if (item.icon.iconType == "WHAT_TO_WATCH" && gfconfig.homeToWhatToWatch) {
                item.formattedTitle = {
                    simpleText: getString("whatToWatch", yt.config_.HL)
                };
            }

            if (item.icon.iconType == "TAB_SHORTS" && gfconfig.remove.shorts) {
                mainSection.splice(i, 1);
                i--;
            }

            if (item.icon.iconType == "SUBSCRIPTIONS") {
                if (gfconfig.addMyChannel && isSignedIn()) {
                    var yourVideos = getItemByIcon(sections, "MY_VIDEOS");
                    var ucid = yourVideos.guideEntryRenderer.navigationEndpoint.urlEndpoint.url.replace(VIDEOS_URL_REGEX, "");

                    mainSection.splice(i, 0, {
                        guideEntryRenderer: {
                            navigationEndpoint: {
                                clickTrackingParams: "CBwQtSwYASITCNqYh-qO_fACFcoRrQYdP44D9Q==",
                                commandMetadata: {
                                    webCommandMetadata: {
                                        url: "/channel/" + ucid,
                                        webPageType: "WEB_PAGE_TYPE_CHANNEL",
                                        rootVe: 6827,
                                        apiUrl: "/youtubei/v1/browse"
                                    }
                                },
                                browseEndpoint: {
                                    browseId: ucid
                                }
                            },
                            icon: {
                                iconType: "ACCOUNT_CIRCLE"
                            },
                            trackingParams: "CBwQtSwYASITCNqYh-qO_fACFcoRrQYdP44D9Q==",
                            formattedTitle: {
                                simpleText: getString("myChannel", yt.config_.HL)
                            },
                            accessibility: {
                                accessibilityData: {
                                    label: getString("myChannel", yt.config_.HL)
                                }
                            }
                        }
                    });
                    i++;
                }

                if (gfconfig.addTrending) {
                    mainSection.splice(i, 0, getItemByIcon(sections, "TRENDING"));
                    i++;
                }

                if (gfconfig.historyItemSignedOut && !isSignedIn()) {
                 ...