☰

YouTube 超快聊天

让您的 YouTube 直播聊天即时滚动，不经过平滑转换 CSS。

当前为 2023-07-11 提交的版本，查看 最新版本。

  1. // ==UserScript==
  2. // @name                YouTube Super Fast Chat
  3. // @version             0.5.22
  4. // @license             MIT
  5. // @name:ja             YouTube スーパーファーストチャット
  6. // @name:zh-TW          YouTube 超快聊天
  7. // @name:zh-CN          YouTube 超快聊天
  8. // @namespace           UserScript
  9. // @match               https://www.youtube.com/live_chat*
  10. // @author              CY Fung
  11. // @require             https://greasyfork.org/scripts/465819-api-for-customelements-in-youtube/code/API%20for%20CustomElements%20in%20YouTube.js?version=1215280
  12. // @run-at              document-start
  13. // @grant               none
  14. // @unwrap
  15. // @allFrames           true
  16. // @inject-into         page
  17. //
  18. // @description         To make your YouTube Live Chat scroll instantly without smoothing transform CSS
  19. // @description:ja      YouTubeライブチャットをスムーズな変形CSSなしで瞬時にスクロールさせるために。
  20. // @description:zh-TW   讓您的 YouTube 直播聊天即時滾動，不經過平滑轉換 CSS。
  21. // @description:zh-CN   让您的 YouTube 直播聊天即时滚动，不经过平滑转换 CSS。
  22. //
  23. // ==/UserScript==
  24.  
  25. ((__CONTEXT__) => {
  26.  
  27.     // const ACTIVE_DEFERRED_APPEND = false; // somehow buggy
  28.  
  29.     // const ACTIVE_CONTENT_VISIBILITY = true;
  30.     // const ACTIVE_CONTAIN_SIZE = true;
  31.  
  32.     const addCss = () => document.head.appendChild(document.createElement('style')).textContent = `
  33.  
  34.  
  35.     @supports (contain:layout paint style) and (content-visibility:auto) and (contain-intrinsic-size:auto var(--wsr94)) {
  36.  
  37.       [wSr93="hidden"]:nth-last-child(n+4) {
  38.         --wsr93-content-visibility: auto;
  39.         contain-intrinsic-size: auto var(--wsr94);
  40.       }
  41.  
  42.     }
  43.  
  44.     @supports (contain:layout paint style) {
  45.  
  46.       [wSr93] {
  47.         --wsr93-contain: layout style;
  48.         contain: var(--wsr93-contain, unset) !important;
  49.         box-sizing: border-box !important;
  50.         content-visibility: var(--wsr93-content-visibility, visible);
  51.       }
  52.       [wSr93="hidden"] { /* initial->[wSr93]->[wSr93="visible"]->[wSr93="hidden"] => reliable rendered height */
  53.         --wsr93-contain: size layout style;
  54.         height: var(--wsr94);
  55.       }
  56.  
  57.  
  58.       /* ------------------------------------------------------------------------------------------------------------- */
  59.  
  60.       yt-live-chat-author-chip #chat-badges.yt-live-chat-author-chip, yt-live-chat-author-chip #chat-badges.yt-live-chat-author-chip yt-live-chat-author-badge-renderer, yt-live-chat-author-chip #chat-badges.yt-live-chat-author-chip yt-live-chat-author-badge-renderer #image, yt-live-chat-author-chip #chat-badges.yt-live-chat-author-chip yt-live-chat-author-badge-renderer #image img {
  61.         contain: layout style;
  62.       }
  63.  
  64.       body yt-live-chat-app {
  65.         contain: size layout paint style;
  66.         overflow: hidden;
  67.       }
  68.  
  69.       #items.style-scope.yt-live-chat-item-list-renderer {
  70.         contain: layout paint style;
  71.       }
  72.  
  73.       #item-offset.style-scope.yt-live-chat-item-list-renderer {
  74.         contain: style;
  75.       }
  76.  
  77.       #item-scroller.style-scope.yt-live-chat-item-list-renderer {
  78.         contain: size style;
  79.       }
  80.  
  81.       #contents.style-scope.yt-live-chat-item-list-renderer, #chat.style-scope.yt-live-chat-renderer, img.style-scope.yt-img-shadow[width][height] {
  82.         contain: size layout paint style;
  83.       }
  84.  
  85.       .style-scope.yt-live-chat-ticker-renderer[role="button"][aria-label], .style-scope.yt-live-chat-ticker-renderer[role="button"][aria-label] > #container {
  86.         contain: layout paint style;
  87.       }
  88.  
  89.       yt-live-chat-text-message-renderer.style-scope.yt-live-chat-item-list-renderer, yt-live-chat-membership-item-renderer.style-scope.yt-live-chat-item-list-renderer, yt-live-chat-paid-message-renderer.style-scope.yt-live-chat-item-list-renderer, yt-live-chat-banner-manager.style-scope.yt-live-chat-item-list-renderer {
  90.         contain: layout style;
  91.       }
  92.  
  93.       tp-yt-paper-tooltip[style*="inset"][role="tooltip"] {
  94.         contain: layout paint style;
  95.       }
  96.  
  97.       /* ------------------------------------------------------------------------------------------------------------- */
  98.  
  99.     }
  100.  
  101.     @supports (color: var(--general)) {
  102.  
  103.         #item-offset.style-scope.yt-live-chat-item-list-renderer > #items.style-scope.yt-live-chat-item-list-renderer {
  104.             position: static !important;
  105.         }
  106.  
  107.         .ytp-contextmenu[class],
  108.         .toggle-button.tp-yt-paper-toggle-button[class],
  109.         .yt-spec-touch-feedback-shape__fill[class],
  110.         .fill.yt-interaction[class],
  111.         .ytp-videowall-still-info-content[class],
  112.         .ytp-suggestion-image[class] {
  113.           will-change: unset !important;
  114.         }
  115.  
  116.         yt-img-shadow[height][width] {
  117.           content-visibility: visible !important;
  118.         }
  119.  
  120.         yt-live-chat-item-list-renderer:not([allow-scroll]) #item-scroller.yt-live-chat-item-list-renderer {
  121.             overflow-y: scroll;
  122.             padding-right: 0;
  123.         }
  124.  
  125.  
  126.         /* optional */
  127.         #item-offset.style-scope.yt-live-chat-item-list-renderer {
  128.         height: auto !important;
  129.         min-height: unset !important;
  130.         }
  131.  
  132.         #items.style-scope.yt-live-chat-item-list-renderer {
  133.         transform: translateY(0px) !important;
  134.         }
  135.  
  136.         /* optional */
  137.         yt-icon[icon="down_arrow"] > *, yt-icon-button#show-more > * {
  138.         pointer-events: none !important;
  139.         }
  140.  
  141.         #continuations, #continuations * {
  142.             contain: strict;
  143.             position: fixed;
  144.             top: 2px;
  145.             height: 1px;
  146.             width: 2px;
  147.             height: 1px;
  148.             visibility: collapse;
  149.         }
  150.  
  151.         yt-live-chat-renderer[has-action-panel-renderer] #show-more.yt-live-chat-item-list-renderer{
  152.             top: 4px;
  153.             transition-property: top;
  154.             bottom: unset;
  155.         }
  156.  
  157.         yt-live-chat-renderer[has-action-panel-renderer] #show-more.yt-live-chat-item-list-renderer[disabled]{
  158.             top: -42px;
  159.         }
  160.  
  161.         html #panel-pages.yt-live-chat-renderer > #input-panel.yt-live-chat-renderer:not(:empty) {
  162.             --yt-live-chat-action-panel-top-border: none;
  163.         }
  164.  
  165.         html #panel-pages.yt-live-chat-renderer > #input-panel.yt-live-chat-renderer.iron-selected > *:first-child {
  166.             border-top: 1px solid var(--yt-live-chat-panel-pages-border-color);
  167.         }
  168.  
  169.         html #panel-pages.yt-live-chat-renderer {
  170.             border-top: 0;
  171.             border-bottom: 0;
  172.         }
  173.  
  174.         #input-panel #picker-buttons yt-live-chat-icon-toggle-button-renderer#product-picker {
  175.             overflow: hidden;
  176.             contain: layout paint style;
  177.         }
  178.  
  179.     }
  180.  
  181.     `;
  182.  
  183.     const { Promise, requestAnimationFrame, IntersectionObserver } = __CONTEXT__;
  184.  
  185.  
  186.     const isContainSupport = CSS.supports('contain', 'layout paint style');
  187.     if (!isContainSupport) {
  188.         console.warn("Your browser does not support css property 'contain'.\nPlease upgrade to the latest version.".trim());
  189.     }
  190.  
  191.     // const APPLY_delayAppendChild = false;
  192.  
  193.     // let activeDeferredAppendChild = false; // deprecated
  194.  
  195.     // let delayedAppendParentWS = new WeakSet();
  196.     // let delayedAppendOperations = [];
  197.     // let commonAppendParentStackSet = new Set();
  198.  
  199.     // let firstVisibleItemDetected = false; // deprecated
  200.  
  201.     const sp7 = Symbol();
  202.  
  203.  
  204.     let dt0 = Date.now() - 2000;
  205.     const dateNow = () => Date.now() - dt0;
  206.     // let lastScroll = 0;
  207.     // let lastLShow = 0;
  208.     let lastWheel = 0;
  209.  
  210.     const proxyHelperFn = (dummy) => ({
  211.  
  212.         get(target, prop) {
  213.             return (prop in dummy) ? dummy[prop] : prop === sp7 ? target : target[prop];
  214.         },
  215.         set(target, prop, value) {
  216.             if (!(prop in dummy)) {
  217.                 target[prop] = value;
  218.             }
  219.             return true;
  220.         },
  221.         has(target, prop) {
  222.             return (prop in target)
  223.         },
  224.         deleteProperty(target, prop) {
  225.             return true;
  226.         },
  227.         ownKeys(target) {
  228.             return Object.keys(target);
  229.         },
  230.         defineProperty(target, key, descriptor) {
  231.             return Object.defineProperty(target, key, descriptor);
  232.         },
  233.         getOwnPropertyDescriptor(target, key) {
  234.             return Object.getOwnPropertyDescriptor(target, key);
  235.         },
  236.  
  237.     });
  238.  
  239.     const tickerContainerSetAttribute = function (attrName, attrValue) { // ensure '14.30000001%'.toFixed(1)
  240.  
  241.         let yd = (this.__dataHost || (this.inst || 0).__dataHost).__data;
  242.  
  243.         if (arguments.length === 2 && attrName === 'style' && yd && attrValue) {
  244.  
  245.             // let v = yd.containerStyle.privateDoNotAccessOrElseSafeStyleWrappedValue_;
  246.             let v = `${attrValue}`;
  247.             // conside a ticker is 101px width
  248.             // 1% = 1.01px
  249.             // 0.2% = 0.202px
  250.  
  251.  
  252.             const ratio1 = (yd.ratio * 100);
  253.             if (ratio1 > -1) { // avoid NaN
  254.  
  255.                 // countdownDurationMs
  256.                 // 600000 - 0.2%    <1% = 6s>  <0.2% = 1.2s>
  257.                 // 300000 - 0.5%    <1% = 3s>  <0.5% = 1.5s>
  258.                 // 150000 - 1%    <1% = 1.5s>
  259.                 // 75000 - 2%    <1% =0.75s > <2% = 1.5s>
  260.                 // 30000 - 5%    <1% =0.3s > <5% = 1.5s>
  261.  
  262.                 // 99px * 5% = 4.95px
  263.  
  264.                 // 15000 - 10%    <1% =0.15s > <10% = 1.5s>
  265.  
  266.  
  267.  
  268.  
  269.                 // 1% Duration
  270.  
  271.                 let ratio2 = ratio1;
  272.  
  273.                 const ydd = yd.data;
  274.                 const d1 = ydd.durationSec;
  275.                 const d2 = ydd.fullDurationSec;
  276.  
  277.                 if (d1 === d2 && d1 > 1) {
  278.  
  279.                     if (d1 > 400) ratio2 = Math.round(ratio2 * 5) / 5; // 0.2%
  280.                     else if (d1 > 200) ratio2 = Math.round(ratio2 * 2) / 2; // 0.5%
  281.                     else if (d1 > 100) ratio2 = Math.round(ratio2 * 1) / 1; // 1%
  282.                     else if (d1 > 50) ratio2 = Math.round(ratio2 * 0.5) / 0.5; // 2%
  283.                     else if (d1 > 25) ratio2 = Math.round(ratio2 * 0.2) / 0.2; // 5% (max => 99px * 5% = 4.95px)
  284.                     else ratio2 = Math.round(ratio2 * 0.2) / 0.2;
  285.  
  286.                 } else {
  287.                     ratio2 = Math.round(ratio2 * 5) / 5; // 0.2% (min)
  288.                 }
  289.  
  290.                 // ratio2 = Math.round(ratio2 * 5) / 5;
  291.                 ratio2 = ratio2.toFixed(1)
  292.                 v = v.replace(`${ratio1}%`, `${ratio2}%`).replace(`${ratio1}%`, `${ratio2}%`)
  293.  
  294.                 if (yd.__style_last__ === v) return;
  295.                 yd.__style_last__ = v;
  296.                 // do not consider any delay here.
  297.                 // it shall be inside the looping for all properties changes. all the css background ops are in the same microtask.
  298.  
  299.             }
  300.  
  301.             HTMLElement.prototype.setAttribute.call(this, attrName, v);
  302.  
  303.  
  304.         } else {
  305.             HTMLElement.prototype.setAttribute.apply(this, arguments);
  306.         }
  307.  
  308.     };
  309.  
  310.     const fxOperator = (proto, propertyName) => {
  311.         let propertyDescriptorGetter = null;
  312.         try {
  313.             propertyDescriptorGetter = Object.getOwnPropertyDescriptor(proto, propertyName).get;
  314.         } catch (e) { }
  315.         return typeof propertyDescriptorGetter === 'function' ? (e) => propertyDescriptorGetter.call(e) : (e) => e[propertyName];
  316.     };
  317.  
  318.     const nodeParent = fxOperator(Node.prototype, 'parentNode');
  319.     // const nFirstElem = fxOperator(HTMLElement.prototype, 'firstElementChild');
  320.     const nPrevElem = fxOperator(HTMLElement.prototype, 'previousElementSibling');
  321.     const nNextElem = fxOperator(HTMLElement.prototype, 'nextElementSibling');
  322.     const nLastElem = fxOperator(HTMLElement.prototype, 'lastElementChild');
  323.  
  324.  
  325.     /* globals WeakRef:false */
  326.  
  327.     /** @type {(o: Object | null) => WeakRef | null} */
  328.     const mWeakRef = typeof WeakRef === 'function' ? (o => o ? new WeakRef(o) : null) : (o => o || null); // typeof InvalidVar == 'undefined'
  329.  
  330.     /** @type {(wr: Object | null) => Object | null} */
  331.     const kRef = (wr => (wr && wr.deref) ? wr.deref() : wr);
  332.  
  333.     const watchUserCSS = () => {
  334.  
  335.         // if (!CSS.supports('contain-intrinsic-size', 'auto var(--wsr94)')) return;
  336.  
  337.         const getElemFromWR = (nr) => {
  338.             const n = kRef(nr);
  339.             if (n && n.isConnected) return n;
  340.             return null;
  341.         }
  342.  
  343.         const clearContentVisibilitySizing = () => {
  344.             Promise.resolve().then(() => {
  345.  
  346.                 let btnShowMoreWR = mWeakRef(document.querySelector('#show-more[disabled]'));
  347.  
  348.                 let lastVisibleItemWR = null;
  349.                 for (const elm of document.querySelectorAll('[wSr93]')) {
  350.                     if (elm.getAttribute('wSr93') === 'visible') lastVisibleItemWR = mWeakRef(elm);
  351.                     elm.setAttribute('wSr93', '');
  352.                     // custom CSS property --wsr94 not working when attribute wSr93 removed
  353.                 }
  354.                 requestAnimationFrame(() => {
  355.                     const btnShowMore = getElemFromWR(btnShowMoreWR); btnShowMoreWR = null;
  356.                     if (btnShowMore) btnShowMore.click();
  357.                     else {
  358.                         // would not work if switch it frequently
  359.                         const lastVisibleItem = getElemFromWR(lastVisibleItemWR); lastVisibleItemWR = null;
  360.                         if (lastVisibleItem) {
  361.  
  362.                             Promise.resolve()
  363.                                 .then(() => lastVisibleItem.scrollIntoView())
  364.                                 .then(() => lastVisibleItem.scrollIntoView(false))
  365.                                 .then(() => lastVisibleItem.scrollIntoView({ behavior: "instant", block: "end", inline: "nearest" }))
  366.                                 .catch(e => { }) // break the chain when method not callable
  367.  
  368.                         }
  369.                     }
  370.                 })
  371.  
  372.             })
  373.  
  374.         }
  375.  
  376.         const mutObserver = new MutationObserver((mutations) => {
  377.             for (const mutation of mutations) {
  378.                 if ((mutation.addedNodes || 0).length >= 1) {
  379.                     for (const addedNode of mutation.addedNodes) {
  380.                         if (addedNode.nodeName === 'STYLE') {
  381.                             clearContentVisibilitySizing();
  382.                             return;
  383.                         }
  384.                     }
  385.                 }
  386.                 if ((mutation.removedNodes || 0).length >= 1) {
  387.                     for (const removedNode of mutation.removedNodes) {
  388.                         if (removedNode.nodeName === 'STYLE') {
  389.                             clearContentVisibilitySizing();
  390.                             return;
  391.                         }
  392.                     }
  393.                 }
  394.             }
  395.         });
  396.  
  397.         mutObserver.observe(document.documentElement, {
  398.             childList: true,
  399.             subtree: false
  400.         })
  401.  
  402.         mutObserver.observe(document.head, {
  403.             childList: true,
  404.             subtree: false
  405.         })
  406.         mutObserver.observe(document.body, {
  407.             childList: true,
  408.             subtree: false
  409.         });
  410.  
  411.     }
  412.  
  413.     const setupStyle = (m1, m2) => {
  414.  
  415.         const dummy1v = {
  416.             transform: '',
  417.             height: '',
  418.             minHeight: '',
  419.             paddingBottom: '',
  420.             paddingTop: ''
  421.         };
  422.         for (const k of ['toString', 'getPropertyPriority', 'getPropertyValue', 'item', 'removeProperty', 'setProperty']) {
  423.             dummy1v[k] = ((k) => (function () { const style = this[sp7]; return style[k](...arguments); }))(k)
  424.         }
  425.  
  426.         const dummy1p = proxyHelperFn(dummy1v);
  427.         const sp1v = new Proxy(m1.style, dummy1p);
  428.         const sp2v = new Proxy(m2.style, dummy1p);
  429.         Object.defineProperty(m1, 'style', { get() { return sp1v }, set() { }, enumerable: true, configurable: true });
  430.         Object.defineProperty(m2, 'style', { get() { return sp2v }, set() { }, enumerable: true, configurable: true });
  431.         m1.removeAttribute("style");
  432.         m2.removeAttribute("style");
  433.  
  434.     }
  435.  
  436.  
  437.     class WillChangeController {
  438.         constructor(itemScroller, willChangeValue) {
  439.             this.element = itemScroller;
  440.             this.counter = 0;
  441.             this.active = false;
  442.             this.willChangeValue = willChangeValue;
  443.         }
  444.  
  445.         beforeOper() {
  446.             if (!this.active) {
  447.                 this.active = true;
  448.                 this.element.style.willChange = this.willChangeValue;
  449.             }
  450.             this.counter++;
  451.         }
  452.  
  453.         afterOper() {
  454.             const c = this.counter;
  455.             requestAnimationFrame(() => {
  456.                 if (c === this.counter) {
  457.                     this.active = false;
  458.                     this.element.style.willChange = '';
  459.                 }
  460.             })
  461.         }
  462.  
  463.         release() {
  464.             const element = this.element;
  465.             this.element = null;
  466.             this.counter = 1e16;
  467.             this.active = false;
  468.             try {
  469.                 element.style.willChange = '';
  470.             } catch (e) { }
  471.         }
  472.  
  473.     }
  474.  
  475.  
  476.     customYtElements.onRegistryReady(() => {
  477.  
  478.         let scrollWillChangeController = null;
  479.         let contensWillChangeController = null;
  480.  
  481.         // as it links to event handling, it has to be injected using immediateCallback
  482.         customYtElements.whenRegistered('yt-live-chat-item-list-renderer', (cProto) => {
  483.  
  484.             const mclp = cProto;
  485.             console.assert(typeof mclp.scrollToBottom_ === 'function')
  486.             console.assert(typeof mclp.scrollToBottom66_ !== 'function')
  487.             console.assert(typeof mclp.flushActiveItems_ === 'function')
  488.             console.assert(typeof mclp.flushActiveItems66_ !== 'function')
  489.  
  490.  
  491.             mclp.__intermediate_delay__ = null;
  492.  
  493.             mclp.scrollToBottom66_ = mclp.scrollToBottom_;
  494.             mclp.scrollToBottom_ = function () {
  495.                 const cnt = this;
  496.                 const itemScroller = cnt.itemScroller;
  497.                 if (scrollWillChangeController && scrollWillChangeController.element !== itemScroller) {
  498.                     scrollWillChangeController.release();
  499.                     scrollWillChangeController = null;
  500.                 }
  501.                 if (!scrollWillChangeController) scrollWillChangeController = new WillChangeController(itemScroller, 'scroll-position');
  502.                 const wcController = scrollWillChangeController;
  503.                 wcController.beforeOper();
  504.                 cnt.__intermediate_delay__ = new Promise(resolve => {
  505.                     Promise.resolve().then(() => {
  506.                         cnt.scrollToBottom66_();
  507.                     }).then(() => {
  508.                         wcController.afterOper();
  509.                         resolve();
  510.                     });
  511.                 });
  512.             }
  513.  
  514.             mclp.flushActiveItems77_ = async function () {
  515.                 try {
  516.  
  517.                     const cnt = this;
  518.                     if (lastFlushActiveItemsCalled > 1e9) lastFlushActiveItemsCalled = 9;
  519.                     let tid = ++lastFlushActiveItemsCalled;
  520.                     if (tid !== lastFlushActiveItemsCalled || cnt.isAttached === false || (cnt.hostElement || cnt).isConnected === false) return;
  521.                     if (!cnt.activeItems_ || cnt.activeItems_.length === 0) return;
  522.                     if (cnt.canScrollToBottom_()) {
  523.                         let immd = cnt.__intermediate_delay__;
  524.                         await new Promise(requestAnimationFrame);
  525.                         if (tid !== lastFlushActiveItemsCalled || cnt.isAttached === false || (cnt.hostElement || cnt).isConnected === false) return;
  526.                         if (!cnt.activeItems_ || cnt.activeItems_.length === 0) return;
  527.  
  528.                         const items = (cnt.$ || 0).items;
  529.                         if (contensWillChangeController && contensWillChangeController.element !== items) {
  530.                             contensWillChangeController.release();
  531.                             contensWillChangeController = null;
  532.                         }
  533.                         if (!contensWillChangeController) contensWillChangeController = new WillChangeController(items, 'contents');
  534.                         const wcController = contensWillChangeController;
  535.                         cnt.__intermediate_delay__ = Promise.all([cnt.__intermediate_delay__ || null, immd || null]);
  536.                         wcController.beforeOper();
  537.                         await Promise.resolve();
  538.                         const len1 = cnt.activeItems_.length;
  539.                         cnt.flushActiveItems66_();
  540.                         const len2 = cnt.activeItems_.length;
  541.                         let bAsync = len1 !== len2;
  542.                         await Promise.resolve();
  543.                         if (bAsync) {
  544.                             cnt.async(() => {
  545.                                 wcController.afterOper();
  546.                             });
  547.                         } else {
  548.                             wcController.afterOper();
  549.                         }
  550.                         return 1;
  551.                     } else {
  552.                         cnt.flushActiveItems66_();
  553.                         return 2;
  554.                     }
  555.                 } catch (e) {
  556.                     console.warn(e);
  557.                 }
  558.             }
  559.  
  560.             mclp.flushActiveItems66_ = mclp.flushActiveItems_;
  561.             let lastFlushActiveItemsCalled = 0;
  562.             mclp.flushActiveItems_ = function () {
  563.                 const cnt = this;
  564.  
  565.                 if (arguments.length !== 0 || !cnt.activeItems_ || !cnt.canScrollToBottom_) return cnt.flushActiveItems66_.apply(this, arguments);
  566.  
  567.                 if (cnt.activeItems_.length === 0) {
  568.                     cnt.__intermediate_delay__ = null;
  569.                     return;
  570.                 }
  571.  
  572.                 const cntData = ((cnt || 0).data || 0);
  573.                 if (cntData.maxItemsToDisplay > 90) cntData.maxItemsToDisplay = 90;
  574.  
  575.                 // ignore previous __intermediate_delay__ and create a new one
  576.                 cnt.__intermediate_delay__ = new Promise(resolve => {
  577.                     cnt.flushActiveItems77_().then(rt => {
  578.                         if (rt === 1) resolve(1); // success, scroll to bottom
  579.                         else if (rt === 2) resolve(2); // success, trim
  580.                         else resolve(-1); // skip
  581.                     });
  582.                 });
  583.  
  584.             }
  585.  
  586.             mclp.async66 = mclp.async;
  587.             mclp.async = function () {
  588.                 // ensure the previous operation is done
  589.                 // .async is usually after the time consuming functions like flushActiveItems_ and scrollToBottom_
  590.  
  591.                 const stack = new Error().stack;
  592.                 const isFlushAsync = stack.indexOf('flushActiveItems_') >= 0;
  593.                 (this.__intermediate_delay__ || Promise.resolve()).then(rk => {
  594.                     if (isFlushAsync) {
  595.                         if (rk < 0) return;
  596.                         if (rk === 2 && arguments[0] === this.maybeScrollToBottom_) return;
  597.                     }
  598.                     this.async66.apply(this, arguments);
  599.                 });
  600.  
  601.             }
  602.  
  603.         })
  604.  
  605.     });
  606.  
  607.     const getProto = (element) => {
  608.         let proto = null;
  609.         if (element) {
  610.             if (element.inst) proto = element.inst.constructor.prototype;
  611.             else proto = element.constructor.prototype;
  612.         }
  613.         return proto || null;
  614.     }
  615.  
  616.     let done = 0;
  617.     let main = async (q) => {
  618.  
  619.         if (done) return;
  620.  
  621.         if (!q) return;
  622.         let m1 = nodeParent(q);
  623.         let m2 = q;
  624.         if (!(m1 && m1.id === 'item-offset' && m2 && m2.id === 'items')) return;
  625.  
  626.         done = 1;
  627.  
  628.         Promise.resolve().then(watchUserCSS);
  629.  
  630.         addCss();
  631.  
  632.         setupStyle(m1, m2);
  633.  
  634.         let lcRendererWR = null;
  635.  
  636.         const lcRendererElm = () => {
  637.             let lcRenderer = kRef(lcRendererWR);
  638.             if (!lcRenderer || !lcRenderer.isConnected) {
  639.                 lcRenderer = document.querySelector('yt-live-chat-item-list-renderer.yt-live-chat-renderer');
  640.                 lcRendererWR = lcRenderer ? mWeakRef(lcRenderer) : null;
  641.             }
  642.             return lcRenderer
  643.         };
  644.  
  645.         let hasFirstShowMore = false;
  646.  
  647.         const visObserverFn = (entry) => {
  648.  
  649.             const target = entry.target;
  650.             if (!target) return;
  651.             let isVisible = entry.isIntersecting === true && entry.intersectionRatio > 0.5;
  652.             const h = entry.boundingClientRect.height;
  653.             if (h < 16) { // wrong: 8 (padding/margin); standard: 32; test: 16 or 20
  654.                 // e.g. under fullscreen. the element created but not rendered.
  655.                 target.setAttribute('wSr93', '');
  656.                 return;
  657.             }
  658.             if (isVisible) {
  659.                 target.style.setProperty('--wsr94', h + 'px');
  660.                 target.setAttribute('wSr93', 'visible');
  661.                 if (nNextElem(target) === null) {
  662.                     // firstVisibleItemDetected = true;
  663.                     /*
  664.                       if (dateNow() - lastScroll < 80) {
  665.                           lastLShow = 0;
  666.                           lastScroll = 0;
  667.                           Promise.resolve().then(clickShowMore);
  668.                       } else {
  669.                           lastLShow = dateNow();
  670.                       }
  671.                       */
  672.                     // lastLShow = dateNow();
  673.                 } else if (!hasFirstShowMore) { // should more than one item being visible
  674.                     // implement inside visObserver to ensure there is sufficient delay
  675.                     hasFirstShowMore = true;
  676.                     requestAnimationFrame(() => {
  677.                         // foreground page
  678.                         // activeDeferredAppendChild = true;
  679.                         // page visibly ready -> load the latest comments at initial loading
  680.                         const lcRenderer = lcRendererElm();
  681.                         if (lcRenderer) {
  682.                             (lcRenderer.inst || lcRenderer).scrollToBottom_();
  683.                         }
  684.                     });
  685.                 }
  686.             }
  687.             else if (target.getAttribute('wSr93') === 'visible') { // ignore target.getAttribute('wSr93') === '' to avoid wrong sizing
  688.  
  689.                 target.style.setProperty('--wsr94', h + 'px');
  690.                 target.setAttribute('wSr93', 'hidden');
  691.             } // note: might consider 0 < entry.intersectionRatio < 0.5 and target.getAttribute('wSr93') === '' <new last item>
  692.  
  693.         }
  694.  
  695.         const visObserver = new IntersectionObserver((entries) => {
  696.  
  697.             for (const entry of entries) {
  698.  
  699.                 Promise.resolve(entry).then(visObserverFn);
  700.  
  701.             }
  702.  
  703.         }, {
  704.             /*
  705.         root: items,
  706.         rootMargin: "0px",
  707.         threshold: 1.0,
  708.         */
  709.             // root: HTMLElement.prototype.closest.call(m2, '#item-scroller.yt-live-chat-item-list-renderer'), // nullable
  710.             rootMargin: "0px",
  711.             threshold: [0.05, 0.95],
  712.         });
  713.  
  714.         //m2.style.visibility='';
  715.  
  716.         const mutFn = (items) => {
  717.             for (let node = nLastElem(items); node !== null; node = nPrevElem(node)) {
  718.                 if (node.hasAttribute('wSr93')) break;
  719.                 node.setAttribute('wSr93', '');
  720.                 visObserver.observe(node);
  721.             }
  722.         }
  723.  
  724.         const mutObserver = new MutationObserver((mutations) => {
  725.             const items = (mutations[0] || 0).target;
  726.             if (!items) return;
  727.             mutFn(items);
  728.         });
  729.  
  730.         const setupMutObserver = (m2) => {
  731.             mutObserver.disconnect();
  732.             mutObserver.takeRecords();
  733.             if (m2) {
  734.                 mutObserver.observe(m2, {
  735.                     childList: true,
  736.                     subtree: false
  737.                 });
  738.                 mutFn(m2);
  739.             }
  740.         }
  741.  
  742.         setupMutObserver(m2);
  743.  
  744.         const mclp = getProto(document.querySelector('yt-live-chat-item-list-renderer'));
  745.         if (mclp && mclp.attached) {
  746.  
  747.             mclp.attached66 = mclp.attached;
  748.             mclp.attached = function () {
  749.                 let m2 = document.querySelector('#item-offset.style-scope.yt-live-chat-item-list-renderer > #items.style-scope.yt-live-chat-item-list-renderer');
  750.                 let m1 = nodeParent(m2);
  751.                 setupStyle(m1, m2);
  752.                 setupMutObserver(m2);
  753.                 return this.attached66();
  754.             }
  755.  
  756.             mclp.detached66 = mclp.detached;
  757.             mclp.detached = function () {
  758.                 setupMutObserver();
  759.                 return this.detached66();
  760.             }
  761.  
  762.             mclp.canScrollToBottom_ = function () {
  763.                 return this.atBottom && this.allowScroll && !(dateNow() - lastWheel < 80)
  764.             }
  765.  
  766.             mclp.isSmoothScrollEnabled_ = function () {
  767.                 return false;
  768.             }
  769.  
  770.         } else {
  771.             console.warn(`proto.attached for yt-live-chat-item-list-renderer is unavailable.`)
  772.         }
  773.  
  774.  
  775.         let scrollCount = 0;
  776.         document.addEventListener('scroll', (evt) => {
  777.             if (!evt || !evt.isTrusted) return;
  778.             // lastScroll = dateNow();
  779.             if (++scrollCount > 1e9) scrollCount = 9;
  780.         }, { passive: true, capture: true }) // support contain => support passive
  781.  
  782.         // document.addEventListener('scroll', (evt) => {
  783.  
  784.         //     if (!evt || !evt.isTrusted) return;
  785.         //     if (!firstVisibleItemDetected) return;
  786.         //     const isUserAction = dateNow() - lastWheel < 80; // continuous wheel -> continuous scroll -> continuous wheel -> continuous scroll
  787.         //     if (!isUserAction) return;
  788.         //     // lastScroll = dateNow();
  789.  
  790.         // }, { passive: true, capture: true }) // support contain => support passive
  791.  
  792.  
  793.         let lastScrollCount = -1;
  794.         document.addEventListener('wheel', (evt) => {
  795.  
  796.             if (!evt || !evt.isTrusted) return;
  797.             if (lastScrollCount === scrollCount) return;
  798.             lastScrollCount = scrollCount;
  799.             lastWheel = dateNow();
  800.  
  801.         }, { passive: true, capture: true }) // support contain => support passive
  802.  
  803.  
  804.         const fp = (renderer) => {
  805.             const cnt = renderer.inst || renderer;
  806.             const container = (cnt.$ || 0).container;
  807.             if (container) {
  808.                 container.setAttribute = tickerContainerSetAttribute;
  809.             }
  810.         }
  811.         const tags = ["yt-live-chat-ticker-paid-message-item-renderer", "yt-live-chat-ticker-paid-sticker-item-renderer",
  812.             "yt-live-chat-ticker-renderer", "yt-live-chat-ticker-sponsor-item-renderer"];
  813.         for (const tag of tags) {
  814.             const dummy = document.createElement(tag);
  815.  
  816.             const cProto = getProto(dummy);
  817.             if (!cProto || !cProto.attached) {
  818.                 console.warn(`proto.attached for ${tag} is unavailable.`)
  819.                 continue;
  820.             }
  821.  
  822.             const __updateTimeout__ = cProto.updateTimeout;
  823.  
  824.             const canDoUpdateTimeoutReplacement = (() => {
  825.  
  826.                 if (dummy.countdownMs < 1 && dummy.lastCountdownTimeMs < 1 && dummy.countdownMs < 1 && dummy.countdownDurationMs < 1) {
  827.                     return typeof dummy.setContainerWidth === 'function' && typeof dummy.slideDown === 'function';
  828.                 }
  829.                 return false;
  830.  
  831.             })(dummy.inst || dummy) && ((__updateTimeout__ + "").indexOf("window.requestAnimationFrame(this.updateTimeout.bind(this))") > 0);
  832.  
  833.  
  834.  
  835.             if (canDoUpdateTimeoutReplacement) {
  836.  
  837.                 const killTicker = (cnt) => {
  838.                     if ("auto" === cnt.hostElement.style.width) cnt.setContainerWidth();
  839.                     cnt.slideDown()
  840.                 };
  841.  
  842.                 cProto.__ratio__ = null;
  843.                 cProto._updateTimeout21_ = function (a) {
  844.  
  845.                     /*
  846.                     let pRatio = this.countdownMs / this.countdownDurationMs;
  847.                     this.countdownMs -= (a - (this.lastCountdownTimeMs || 0));
  848.                     let noMoreCountDown = this.countdownMs < 1e-6;
  849.                     let qRatio = this.countdownMs / this.countdownDurationMs;
  850.                     if(noMoreCountDown){
  851.                         this.countdownMs = 0;
  852.                         this.ratio = 0;
  853.                     } else if( pRatio - qRatio < 0.001 && qRatio < pRatio){
  854.  
  855.                     }else{
  856.                         this.ratio = qRatio;
  857.                     }
  858.                     */
  859.  
  860.                     this.countdownMs -= (a - (this.lastCountdownTimeMs || 0));
  861.  
  862.                     let currentRatio = this.__ratio__;
  863.                     let tdv = this.countdownMs / this.countdownDurationMs;
  864.                     let nextRatio = Math.round(tdv * 500) / 500; // might generate 0.143000000001
  865.  
  866.                     const validCountDown = nextRatio > 0;
  867.                     const isAttached = this.isAttached;
  868.  
  869.                     if (!validCountDown) {
  870.  
  871.                         this.lastCountdownTimeMs = null;
  872.  
  873.                         this.countdownMs = 0;
  874.                         this.__ratio__ = null;
  875.                         this.ratio = 0;
  876.  
  877.                         if (isAttached) Promise.resolve(this).then(killTicker);
  878.  
  879.                     } else if (!isAttached) {
  880.  
  881.                         this.lastCountdownTimeMs = null;
  882.  
  883.                     } else {
  884.  
  885.                         this.lastCountdownTimeMs = a;
  886.  
  887.                         const ratioDiff = currentRatio - nextRatio;  // 0.144 - 0.142 = 0.002
  888.                         if (ratioDiff < 0.001 && ratioDiff > -1e-6) {
  889.                             // ratioDiff = 0
  890.  
  891.                         } else {
  892.                             // ratioDiff = 0.002 / 0.004 ....
  893.                             // OR ratioDiff < 0
  894.  
  895.                             this.__ratio__ = nextRatio;
  896.  
  897.                             this.ratio = nextRatio;
  898.                         }
  899.  
  900.                         return true;
  901.                     }
  902.  
  903.                 };
  904.  
  905.                 cProto._updateTimeout21_ = function (a) {
  906.                     this.countdownMs = Math.max(0, this.countdownMs - (a - (this.lastCountdownTimeMs || 0)));
  907.                     this.ratio = this.countdownMs / this.countdownDurationMs;
  908.                     if (this.isAttached && this.countdownMs) {
  909.                         this.lastCountdownTimeMs = a;
  910.                         return true;
  911.                     } else {
  912.                         this.lastCountdownTimeMs = null;
  913.                         if (this.isAttached) {
  914.                             ("auto" === this.hostElement.style.width && this.setContainerWidth(), this.slideDown())
  915.                         }
  916.                     }
  917.                 }
  918.  
  919.  
  920.                 // temporarily removed; buggy for playback
  921.                 /*
  922.                   cProto.updateTimeout = async function (a) {
  923.  
  924.                       let ret = this._updateTimeout21_(a);
  925.                       while (ret) {
  926.                           let a = await new Promise(resolve => {
  927.                               this.rafId = requestAnimationFrame(resolve)
  928.                           }); // could be never resolve
  929.                           ret = this._updateTimeout21_(a);
  930.                       }
  931.  
  932.                   };
  933.                 */
  934.  
  935.  
  936.             }
  937.  
  938.             cProto.attached77 = cProto.attached
  939.  
  940.             cProto.attached = function () {
  941.                 fp(this.hostElement || this);
  942.                 return this.attached77();
  943.             }
  944.  
  945.             for (const elm of document.getElementsByTagName(tag)) {
  946.                 fp(elm);
  947.             }
  948.  
  949.  
  950.         }
  951.  
  952.     };
  953.  
  954.  
  955.     function onReady() {
  956.         let tmObserver = new MutationObserver(() => {
  957.  
  958.             let p = document.getElementById('items'); // fast
  959.             if (!p) return;
  960.             let q = document.querySelector('#item-offset.style-scope.yt-live-chat-item-list-renderer > #items.style-scope.yt-live-chat-item-list-renderer'); // check
  961.  
  962.             if (q) {
  963.                 tmObserver.disconnect();
  964.                 tmObserver.takeRecords();
  965.                 tmObserver = null;
  966.                 Promise.resolve(q).then((q) => {
  967.                     // confirm Promis.resolve() is resolveable
  968.                     // execute main without direct blocking
  969.                     main(q);
  970.                 })
  971.             }
  972.  
  973.         });
  974.  
  975.         tmObserver.observe(document.body || document.documentElement, {
  976.             childList: true,
  977.             subtree: true
  978.         });
  979.  
  980.     }
  981.  
  982.     Promise.resolve().then(() => {
  983.  
  984.         if (document.readyState !== 'loading') {
  985.             onReady();
  986.         } else {
  987.             window.addEventListener("DOMContentLoaded", onReady, false);
  988.         }
  989.  
  990.     });
  991.  
  992. })({ Promise, requestAnimationFrame, IntersectionObserver });