// ==UserScript==
// @name YouTube EXPERIMENT_FLAGS Tamer (Basic)
// @namespace UserScripts
// @match https://www.youtube.com/*
// @version 0.4.8.1
// @license MIT
// @author CY Fung
// @icon https://github.com/cyfung1031/userscript-supports/raw/main/icons/yt-engine.png
// @description Adjust EXPERIMENT_FLAGS
// @grant none
// @unwrap
// @run-at document-start
// @allFrames true
// @inject-into page
// ==/UserScript==
((__CONTEXT__) => {
// Purpose 1: Remove Obsolete Flags
// Purpose 2: Remove Flags bring no visual difference
// Purpose 3: Enable Flags bring performance boost
const DISABLE_CINEMATICS = false; // standard design
const NO_SerializedExperiment = true;
const KEEP_PLAYER_QUALITY_STICKY = true; // see https://greasyfork.org/scripts/471033/
const DISABLE_serializedExperimentIds = true;
const DISABLE_serializedExperimentFlags = true;
const ALLOW_FLAGS_202404 = true;
const ALLOW_FLAGS_202404_flags41 = new Set([
'action_companion_center_align_description',
'disable_child_node_auto_formatted_strings',
'enable_native_bridge_view_saved_playables',
'enable_shadydom_free_scoped_query_methods',
'enable_skippable_ads_for_unplugged_ad_pod',
'enable_sparkles_web_clickable_description',
'enable_window_constrained_buy_flow_dialog',
'html5_enable_ads_client_monitoring_log_tv',
'is_part_of_any_user_engagement_experiment',
// 'kevlar_chapters_list_view_seek_by_chapter',
// 'kevlar_enable_shorts_prefetch_in_sequence',
// 'kevlar_resolve_command_for_confirm_dialog',
// 'kevlar_shorts_seedless_retry_initial_load',
'live_chat_enable_send_button_in_slow_mode',
'live_chat_web_use_emoji_manager_singleton',
'remove_masthead_channel_banner_on_refresh',
'web_deprecate_service_ajax_map_dependency',
'web_modern_player_settings_quality_bottom',
'web_player_always_enable_auto_translation',
'web_player_enable_cultural_moment_overlay',
'ytidb_fetch_datasync_ids_for_data_cleanup',
'kevlar_tuner_should_test_reuse_components',
]);
const ALLOW_FLAGS_202404_flags47 = new Set([
'web_player_ve_conversion_fixes_for_channel_info',
'web_watch_updated_metadata_server_initial_delay',
// 'trigger_impression_pings_on_view_search_desktop',
]);
const ALLOW_FLAGS_202404_flags11 = new Set([
'use_core_sm',
'use_new_cml',
'web_api_url',
]);
const ENABLE_EXPERIMENT_FLAGS_MAINTAIN_STABLE_LIST = {
defaultValue: true, // performance boost
useExternal: () => typeof localStorage.EXPERIMENT_FLAGS_MAINTAIN_STABLE_LIST !== 'undefined',
externalValue: () => (+localStorage.EXPERIMENT_FLAGS_MAINTAIN_STABLE_LIST ? true : false)
};
const ENABLE_EXPERIMENT_FLAGS_MAINTAIN_REUSE_COMPONENTS = {
defaultValue: true, // not sure
useExternal: () => typeof localStorage.EXPERIMENT_FLAGS_MAINTAIN_REUSE_COMPONENTS !== 'undefined',
externalValue: () => (+localStorage.EXPERIMENT_FLAGS_MAINTAIN_REUSE_COMPONENTS ? true : false)
};
const ENABLE_EXPERIMENT_FLAGS_DEFER_DETACH = {
defaultValue: true, // not sure
useExternal: () => typeof localStorage.ENABLE_EXPERIMENT_FLAGS_DEFER_DETACH !== 'undefined',
externalValue: () => (+localStorage.ENABLE_EXPERIMENT_FLAGS_DEFER_DETACH ? true : false)
};
const ALLOW_ALL_LIVE_CHATS_FLAGS = false;
// TBC
// kevlar_tuner_should_always_use_device_pixel_ratio
// kevlar_tuner_should_clamp_device_pixel_ratio
// kevlar_tuner_clamp_device_pixel_ratio
// kevlar_tuner_should_use_thumbnail_factor
// kevlar_tuner_thumbnail_factor
// kevlar_tuner_min_thumbnail_quality
// kevlar_tuner_max_thumbnail_quality
// kevlar_tuner_should_test_visibility_time_between_jobs
// kevlar_tuner_visibility_time_between_jobs_ms
// kevlar_tuner_default_comments_delay
// kevlar_tuner_run_default_comments_delay
let settled = null;
// cinematic feature is no longer an experimential feature.
// It has been officially implemented.
// To disable cinematics, the user shall use other userscripts or just turn off the option in the video options.
const getSettingValue = (fm) => fm.useExternal() ? fm.externalValue() : fm.defaultValue;
const win = this instanceof Window ? this : window;
// Create a unique key for the script and check if it is already running
const hkey_script = 'jmimcvowrlzl';
if (win[hkey_script]) throw new Error('Duplicated Userscript Calling'); // avoid duplicated scripting
win[hkey_script] = true;
/** @type {globalThis.PromiseConstructor} */
const Promise = ((async () => { })()).constructor;
let isMainWindow = false;
let mzFlagDetected = new Set();
let zPlayerKevlar = false;
try {
isMainWindow = window.document === window.top.document
} catch (e) { }
function fixSerializedExperiment(conf) {
if (DISABLE_serializedExperimentIds && typeof conf.serializedExperimentIds === 'string') {
let ids = conf.serializedExperimentIds.split(',');
let newIds = [];
for (const id of ids) {
let keep = false;
if (keep) {
newIds.push(id);
}
}
conf.serializedExperimentIds = newIds.join(',');
}
if (DISABLE_serializedExperimentFlags && typeof conf.serializedExperimentFlags === 'string') {
const fg = conf.serializedExperimentFlags;
const rx = /(^|&)(\w+)=([^=&|\s\{\}\[\]\(\)?]*)/g;
let res = [];
for (let m; m = rx.exec(fg);) {
let key = m[2];
let value = m[3];
let keep = false;
if (KEEP_PLAYER_QUALITY_STICKY) {
if (key === 'html5_exponential_memory_for_sticky' || key.startsWith('h5_expr_')) {
keep = true;
}
}
if (!DISABLE_CINEMATICS) {
if (key === 'web_cinematic_watch_settings') {
keep = true;
}
}
if (keep) res.push(`${key}=${value}`);
}
conf.serializedExperimentFlags = res.join('&');
}
}
const all_live_chat_flags = `live_chat_banner_expansion_fix
live_chat_enable_mod_view
live_chat_enable_qna_banner_overflow_menu_actions
live_chat_enable_qna_channel
live_chat_enable_send_button_in_slow_mode
live_chat_filter_emoji_suggestions
live_chat_increased_min_height
live_chat_over_playlist
live_chat_web_enable_command_handler
live_chat_web_use_emoji_manager_singleton
live_chat_whole_message_clickable`.trim().split(/\s+/)
const hLooper = ((fn) => {
let nativeFnLoaded = false;
let kc1 = 0;
const setIntervalW = setInterval;
const clearIntervalW = clearInterval;
let microDisconnectFn = null;
let fStopLooper = false;
const looperFn = () => {
if (fStopLooper) return;
let config_ = null;
let EXPERIMENT_FLAGS = null;
try {
config_ = yt.config_;
EXPERIMENT_FLAGS = config_.EXPERIMENT_FLAGS
} catch (e) { }
if (EXPERIMENT_FLAGS) {
fn(EXPERIMENT_FLAGS, config_);
if (microDisconnectFn) {
let isYtLoaded = false;
try {
isYtLoaded = typeof ytcfg.set === 'function';
} catch (e) { }
if (isYtLoaded) {
microDisconnectFn();
}
}
}
let playerKevlar = null;
try {
playerKevlar = ytcfg.data_.WEB_PLAYER_CONTEXT_CONFIGS.WEB_PLAYER_CONTEXT_CONFIG_ID_KEVLAR_WATCH;
} catch (e) { }
if (playerKevlar && !zPlayerKevlar) {
zPlayerKevlar = true;
if (NO_SerializedExperiment && typeof playerKevlar.serializedExperimentFlags === 'string' && typeof playerKevlar.serializedExperimentIds === 'string') {
fixSerializedExperiment(playerKevlar);
}
}
};
const controller = {
start() {
kc1 = setIntervalW(looperFn, 1);
(async () => {
while (true && !nativeFnLoaded) {
looperFn();
if (fStopLooper) break;
await (new Promise(requestAnimationFrame));
}
})();
looperFn();
},
/**
*
* @param {Window} __CONTEXT__
*/
setupForCleanContext(__CONTEXT__) {
const { requestAnimationFrame, setInterval, clearInterval, setTimeout, clearTimeout } = __CONTEXT__;
(async () => {
while (true) {
looperFn();
if (fStopLooper) break;
await (new Promise(requestAnimationFrame));
}
})();
let kc2 = setInterval(looperFn, 1);
const marcoDisconnectFn = () => {
if (fStopLooper) return;
Promise.resolve().then(() => {
if (kc1 || kc2) {
kc1 && clearIntervalW(kc1); kc1 = 0;
kc2 && clearInterval(kc2); kc2 = 0;
looperFn();
}
fStopLooper = true;
});
document.removeEventListener('yt-page-data-fetched', marcoDisconnectFn, false);
document.removeEventListener('yt-navigate-finish', marcoDisconnectFn, false);
document.removeEventListener('spfdone', marcoDisconnectFn, false);
};
document.addEventListener('yt-page-data-fetched', marcoDisconnectFn, false);
document.addEventListener('yt-navigate-finish', marcoDisconnectFn, false);
document.addEventListener('spfdone', marcoDisconnectFn, false);
function onReady() {
if (!fStopLooper) {
setTimeout(() => {
!fStopLooper && marcoDisconnectFn();
}, 1000);
}
}
Promise.resolve().then(() => {
if (document.readyState !== 'loading') {
onReady();
} else {
window.addEventListener("DOMContentLoaded", onReady, false);
}
});
nativeFnLoaded = true;
microDisconnectFn = () => Promise.resolve(marcoDisconnectFn).then(setTimeout);
}
};
return controller;
})((EXPERIMENT_FLAGS, config_) => {
if (!EXPERIMENT_FLAGS) return;
if (!settled) {
settled = {
use_maintain_stable_list: getSettingValue(ENABLE_EXPERIMENT_FLAGS_MAINTAIN_STABLE_LIST),
use_maintain_reuse_components: getSettingValue(ENABLE_EXPERIMENT_FLAGS_MAINTAIN_REUSE_COMPONENTS),
use_defer_detach: getSettingValue(ENABLE_EXPERIMENT_FLAGS_DEFER_DETACH),
}
if (settled.use_maintain_stable_list) Promise.resolve().then(() => console.debug("use_maintain_stable_list"));
if (settled.use_maintain_reuse_components) Promise.resolve().then(() => console.debug("use_maintain_reuse_components"));
if (settled.use_defer_detach) Promise.resolve().then(() => console.debug("use_defer_detach"));
}
const { use_maintain_stable_list, use_maintain_reuse_components, use_defer_detach } = settled;
const setFalseFn = (EXPERIMENT_FLAGS) => {
for (const [key, value] of Object.entries(EXPERIMENT_FLAGS)) {
if (value === true) {
// if(key.indexOf('modern')>=0 || key.indexOf('enable')>=0 || key.indexOf('theme')>=0 || key.indexOf('skip')>=0 || key.indexOf('ui')>=0 || key.indexOf('observer')>=0 || key.indexOf('polymer')>=0 )continue;
if (mzFlagDetected.has(key)) continue;
mzFlagDetected.add(key);
const kl = key.length;
const kl7 = kl % 7;
const kl5 = kl % 5;
const kl3 = kl % 3;
const kl2 = kl % 2;
if (ALLOW_FLAGS_202404) {
if (kl === 26) {
if (key === 'disable_features_for_supex') continue;
if (key === 'export_networkless_options') continue;
if (key === 'suppress_error_204_logging') continue;
if (key === 'use_request_time_ms_header') continue;
if (key === 'disable_features_for_supex') continue;
if (key === 'live_chat_channel_activity') continue;
if (key === 'live_chat_web_input_update') continue;
} else if (kl === 41) {
if (key === 'remove_masthead_channel_banner_on_refresh') continue;
if (key === 'ytidb_fetch_datasync_ids_for_data_cleanup') continue;
if (ALLOW_FLAGS_202404_flags41.has(key)) continue;
}
else if (kl === 47) {
if (ALLOW_FLAGS_202404_flags47.has(key)) continue;
} else if (kl === 11) {
if (key === 'defer_menus') continue;
if (ALLOW_FLAGS_202404_flags11.has(key)) continue;
}
}
if (!DISABLE_CINEMATICS) {
if (key === 'kevlar_measure_ambient_mode_idle' || key === 'kevlar_watch_cinematics_invisible' || key === 'web_cinematic_theater_mode' || key === 'web_cinematic_fullscreen') {
continue;
}
let cineKey = key === 'enable_cinematic_blur_desktop_loading' ? 1
: key === 'kevlar_watch_cinematics' ? 2
: key === 'web_cinematic_masthead' ? 3
: key === 'web_watch_cinematics_preferred_reduced_motion_default_disabled' ? 4 : 0;
if (cineKey > 0) {
return;
}
}
if (key.indexOf('kevlar_') >= 0) {
if (kl7 === 2 && kl5 === 2 && kl2 === 1 && kl3 === 1) {
if (key === 'kevlar_rendererstamper_event_listener') continue; // https://github.com/cyfung1031/userscript-supports/issues/11
}
if (kl === 22) {
// kevlar_enable_up_arrow - no use
// kevlar_help_use_locale - might use
// kevlar_refresh_gesture - might use
// kevlar_smart_downloads - might use
// kevlar_thumbnail_fluid
// kevlar_ytb_live_badges
if (key === 'kevlar_ytb_live_badges') continue;
}
if (!use_maintain_stable_list) {
if (key === 'kevlar_tuner_should_test_maintain_stable_list') continue;
if (key === 'kevlar_should_maintain_stable_list') continue;
if (key === 'kevlar_tuner_should_maintain_stable_list') continue; // fallback
}
if (!use_maintain_reuse_components) {
if (key === 'kevlar_tuner_should_test_reuse_components') continue;
if (key === 'kevlar_tuner_should_reuse_components') continue;
if (key === 'kevlar_should_reuse_components') continue; // fallback
}
if (kl7 === 5 && kl5 == 4 && kl2 === 1 && kl3 === 1) {
if (key === 'kevlar_system_icons') continue;
}
// if(key==='kevlar_prefetch_data_augments_network_data') continue;
if (kl7 === 6 && kl5 === 0 && kl3 === 2 && kl2 === 0) { // home page / watch page icons
if (key === 'kevlar_three_dot_ink') continue;
if (key === 'kevlar_use_wil_icons') continue;
if (key === 'kevlar_home_skeleton') continue;
}
if (kl7 === 4 && kl5 === 0 && kl3 === 1 && kl2 === 1) {
if (key === 'kevlar_fluid_touch_scroll') continue;
if (key === 'kevlar_watch_color_update') continue;
if (key === 'kevlar_use_vimio_behavior') continue; // home page - channel icon
}
if (kl3 === 2 && kl5 === 4 && kl2 < 2) { // collapsed meta
// no teaser, use latest collapsed meta design
if (key === 'kevlar_structured_description_content_inline') continue;
if (key === 'kevlar_watch_metadata_refresh') continue;
}
if (kl5 === 3 && kl3 === 1 && kl2 === 0) {
if (key === 'kevlar_watch_js_panel_height') continue; // affect Tabview Youtube
}
} else {
if (ALLOW_ALL_LIVE_CHATS_FLAGS && all_live_chat_flags.indexOf(key) >= 0) {
continue;
/*
*
live_chat_banner_expansion_fix
live_chat_enable_mod_view
live_chat_enable_qna_banner_overflow_menu_actions
live_chat_enable_qna_channel
live_chat_enable_send_button_in_slow_mode
live_chat_filter_emoji_suggestions
live_chat_increased_min_height
live_chat_over_playlist
live_chat_web_enable_command_handler
live_chat_web_use_emoji_manager_singleton
live_chat_whole_message_clickable
*/
}
if (kl7 === 1 && kl5 === 1 && kl2 === 0 && kl3 === 0) {
if (key === 'live_chat_web_enable_command_handler') continue;
}
if (kl7 === 1 && kl5 === 4 && kl3 === 2 && kl2 === 1) {
if (key === 'shorts_desktop_watch_while_p2') continue;
}
if (key === 'web_button_rework') continue;
if (kl7 === 3 && kl5 == 1 && kl2 === 1 && kl3 === 1) {
if (key === 'web_darker_dark_theme_live_chat') continue;
}
if (kl5 === 1 && kl3 === 0 && kl2 === 1 && kl7 === 0) {
if (key === 'web_darker_dark_theme') return; // it also affect cinemtaics
}
if (kl3 === 0 && kl5 === 2) { // modern menu
if (key === 'web_button_rework_with_live') continue;
if (key === 'web_fix_fine_scrubbing_drag') continue;
}
if (kl3 === 1 && kl5 === 4 && kl2 === 1) { // full screen -buggy
if (key === 'external_fullscreen') continue;
}
if (kl3 === 0 && kl5 === 3 && kl2 === 0) { // minimize menu
if (key === 'web_modern_buttons') continue;
if (key === 'web_modern_dialogs') continue;
}
if (kl3 === 1 && kl5 === 0 && kl7 === 5 && kl2 === 0) { // Tabview Youtube - multiline transcript
if (key === 'enable_mixed_direction_formatted_strings') continue;
}
}
// console.log(key)
EXPERIMENT_FLAGS[key] = false;
}
}
}
setFalseFn(EXPERIMENT_FLAGS);
if (config_.EXPERIMENTS_FORCED_FLAGS) setFalseFn(config_.EXPERIMENTS_FORCED_FLAGS);
EXPERIMENT_FLAGS.desktop_delay_player_resizing = false;
EXPERIMENT_FLAGS.web_animated_like = false;
EXPERIMENT_FLAGS.web_animated_like_lazy_load = false;
if (use_maintain_stable_list) {
EXPERIMENT_FLAGS.kevlar_tuner_should_test_maintain_stable_list = true;
EXPERIMENT_FLAGS.kevlar_should_maintain_stable_list = true;
EXPERIMENT_FLAGS.kevlar_tuner_should_maintain_stable_list = true; // fallback
}
if (use_maintain_reuse_components) {
EXPERIMENT_FLAGS.kevlar_tuner_should_test_reuse_components = true;
EXPERIMENT_FLAGS.kevlar_tuner_should_reuse_components = true;
EXPERIMENT_FLAGS.kevlar_should_reuse_components = true; // fallback
}
if (use_defer_detach) {
EXPERIMENT_FLAGS.kevlar_tuner_should_defer_detach = true;
}
// EXPERIMENT_FLAGS.kevlar_prefetch_data_augments_network_data = true; // TBC
});
hLooper.start();
const cleanContext = async (win) => {
const waitFn = requestAnimationFrame; // shall have been binded to window
try {
let mx = 16; // MAX TRIAL
const frameId = 'vanillajs-iframe-v1'
let frame = document.getElementById(frameId);
let removeIframeFn = null;
if (!frame) {
frame = document.createElement('iframe');
frame.id = 'vanillajs-iframe-v1';
frame.sandbox = 'allow-same-origin'; // script cannot be run inside iframe but API can be obtained from iframe
let n = document.createElement('noscript'); // wrap into NOSCRPIT to avoid reflow (layouting)
n.appendChild(frame);
while (!document.documentElement && mx-- > 0) await new Promise(waitFn); // requestAnimationFrame here could get modified by YouTube engine
const root = document.documentElement;
root.appendChild(n); // throw error if root is null due to exceeding MAX TRIAL
removeIframeFn = (setTimeout) => {
const removeIframeOnDocumentReady = (e) => {
e && win.removeEventListener("DOMContentLoaded", removeIframeOnDocumentReady, false);
win = null;
setTimeout(() => {
n.remove();
n = null;
}, 200);
}
if (document.readyState !== 'loading') {
removeIframeOnDocumentReady();
} else {
win.addEventListener("DOMContentLoaded", removeIframeOnDocumentReady, false);
}
}
}
while (!frame.contentWindow && mx-- > 0) await new Promise(waitFn);
const fc = frame.contentWindow;
if (!fc) throw "window is not found."; // throw error if root is null due to exceeding MAX TRIAL
const { requestAnimationFrame, setInterval, setTimeout, clearInterval, clearTimeout } = fc;
const res = { requestAnimationFrame, setInterval, setTimeout, clearInterval, clearTimeout };
for (let k in res) res[k] = res[k].bind(win); // necessary
if (removeIframeFn) Promise.resolve(res.setTimeout).then(removeIframeFn);
return res;
} catch (e) {
console.warn(e);
return null;
}
};
cleanContext(win).then(__CONTEXT__ => {
const { requestAnimationFrame, setInterval, clearInterval, setTimeout, clearTimeout } = __CONTEXT__;
hLooper.setupForCleanContext(__CONTEXT__)
});
if (isMainWindow) {
console.groupCollapsed(
"%cYouTube EXPERIMENT_FLAGS Tamer",
"background-color: #EDE43B ; color: #000 ; font-weight: bold ; padding: 4px ;"
);
console.log("Script is loaded.");
console.log("This might affect the new features when YouTube rolls them out to general users.");
console.log("If you found any issue in using YouTube, please disable this script to check whether the issue is due to this script or not.");
console.groupEnd();
}
})(null);
