virtual-scroller - npm Package Compare versions

Comparing version 1.5.1 to 1.5.2

bundle/virtual-scroller-dom.js

@@ -1,2 +0,2 @@
-!function(e,t){"object"==typeof exports&&"undefined"!=typeof module?module.exports=t():"function"==typeof define&&define.amd?define(t):(e=e||self).VirtualScroller=t()}(this,function(){"use strict";var e="undefined"!=typeof globalThis?globalThis:"undefined"!=typeof window?window:"undefined"!=typeof global?global:"undefined"!=typeof self?self:{};for(var t,n=(function(t){(function(){var e,n,i,r,o,s;"undefined"!=typeof performance&&null!==performance&&performance.now?t.exports=function(){return performance.now()}:"undefined"!=typeof process&&null!==process&&process.hrtime?(t.exports=function(){return(e()-o)/1e6},n=process.hrtime,r=(e=function(){var e;return 1e9*(e=n())[0]+e[1]})(),s=1e9*process.uptime(),o=r-s):Date.now?(t.exports=function(){return Date.now()-i},i=Date.now()):(t.exports=function(){return(new Date).getTime()-i},i=(new Date).getTime())}).call(e)}(t={exports:{}},t.exports),t.exports),i="undefined"==typeof window?e:window,r=["moz","webkit"],o="AnimationFrame",s=i["request"+o],a=i["cancel"+o]||i["cancelRequest"+o],l=0;!s&&l<r.length;l++)s=i[r[l]+"Request"+o],a=i[r[l]+"Cancel"+o]||i[r[l]+"CancelRequest"+o];if(!s||!a){var u=0,h=0,d=[];s=function(e){if(0===d.length){var t=n(),i=Math.max(0,1e3/60-(t-u));u=i+t,setTimeout(function(){var e=d.slice(0);d.length=0;for(var t=0;t<e.length;t++)if(!e[t].cancelled)try{e[t].callback(u)}catch(e){setTimeout(function(){throw e},0)}},Math.round(i))}return d.push({handle:++h,callback:e,cancelled:!1}),h},a=function(e){for(var t=0;t<d.length;t++)d[t].handle===e&&(d[t].cancelled=!0)}}var c=function(e){return s.call(i,e)};c.cancel=function(){a.apply(i,arguments)},c.polyfill=function(e){e||(e=i),e.requestAnimationFrame=s,e.cancelAnimationFrame=a};var m=c.cancel;function f(e,t){var n=Date.now(),i=c(function r(){Date.now()-n>=t?e():i=c(r)});return{clear:function(){return m(i)}}}function g(e){e&&e.clear()}function I(e){return(I="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}function p(e,t){return!t||"object"!==I(t)&&"function"!=typeof t?function(e){if(void 0===e)throw new ReferenceError("this hasn't been initialised - 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VirtualScroller has been switched into \"bypass\" mode (render all items). See: https://gitlab.com/catamphetamine/virtual-scroller/-/issues/1";function k(e){return function(e){if(Array.isArray(e)){for(var t=0,n=new Array(e.length);t<e.length;t++)n[t]=e[t];return n}}(e)||function(e){if(Symbol.iterator in Object(e)||"[object Arguments]"===Object.prototype.toString.call(e))return Array.from(e)}(e)||function(){throw new TypeError("Invalid attempt to spread non-iterable instance")}()}function R(){if(A()){for(var e,t=arguments.length,n=new Array(t),i=0;i<t;i++)n[i]=arguments[i];(e=console).log.apply(e,k(["[virtual-scroller]"].concat(n)))}}function A(){return"undefined"!=typeof window&&window.VirtualScrollerDebug}function T(e,t){for(var n=0;n<t.length;n++){var i=t[n];i.enumerable=i.enumerable||!1,i.configurable=!0,"value"in i&&(i.writable=!0),Object.defineProperty(e,i.key,i)}}var P=function(){function e(t,n){!function(e,t){if(!(e instanceof t))throw new TypeError("Cannot call a class as a 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t=e.childNodes[0],n=e.childNodes[1],i=t.getBoundingClientRect(),r=n.getBoundingClientRect().top-(i.top+i.height);return window.VirtualScrollerDebug&&R("Measure item spacing",r),r}}},{key:"update",value:function(e,t,n){void 0===this.getState().itemSpacing&&(this.getState().itemSpacing=this.getItemSpacing()),void 0!==this.firstMeasuredItemIndex&&(e>this.lastMeasuredItemIndex+1||t<this.firstMeasuredItemIndex-1)&&this.reset();for(var i=this.firstMeasuredItemIndex,r=this.lastMeasuredItemIndex,o=!1,s=e;s<=t;){var a=this._getItemHeight(s,n);void 0!==a&&(this.set(s,a),(void 0===i||s<i)&&(this.measuredItemsHeight+=a,o||(this.firstMeasuredItemIndex=s,o=!0)),(void 0===r||s>r)&&(void 0!==r&&(this.measuredItemsHeight+=a),this.lastMeasuredItemIndex=s)),s++}}},{key:"updateItemHeight",value:function(e,t){var n=this.get(e),i=this._getItemHeight(e,t);void 0!==n&&void 0!==i&&(this.set(e,i),this.measuredItemsHeight+=i-n)}},{key:"getAverage",value:function(){return this.measuredItemsHeight?this.measuredItemsHeight/(this.lastMeasuredItemIndex-this.firstMeasuredItemIndex+1):0}},{key:"get",value:function(e){return this.getState().itemHeights[e]}},{key:"set",value:function(e,t){this.getState().itemHeights[e]=t}},{key:"onPrepend",value:function(e){void 0!==this.firstMeasuredItemIndex&&(this.firstMeasuredItemIndex+=e,this.lastMeasuredItemIndex+=e)}}])&&T(t.prototype,n),i&&T(t,i),e}();function L(e){return(L="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}var M=Object.prototype.hasOwnProperty;function E(e,t){return e===t?0!==e||0!==t||1/e==1/t:e!=e&&t!=t}function U(e){for(var t=1;t<arguments.length;t++){var n=null!=arguments[t]?arguments[t]:{},i=Object.keys(n);"function"==typeof Object.getOwnPropertySymbols&&(i=i.concat(Object.getOwnPropertySymbols(n).filter(function(e){return 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s.updateLayout()}),z(this,"onResize",(i=function(e){if(s.isRendered){var t=s.shouldUpdateLayoutOnScrollableContainerResize(e);"UPDATE_LAYOUT"===t?(R("~ Scrollable container size changed, re-measure item heights. ~"),s.resized=!0,s.setState(s.getInitialLayoutState())):"UPDATE_INDEXES"===t&&s.onUpdateShownItemIndexes({reason:"resize"})}},r=j,function(){for(var e=this,t=arguments.length,n=new Array(t),s=0;s<t;s++)n[s]=arguments[s];clearTimeout(o),o=setTimeout(function(){return i.apply(e,n)},r)})),z(this,"willUpdateState",function(e,t){if(t&&s.preserveScrollPositionOnPrependItems){s.preserveScrollPositionOnPrependItems=void 0;var n=t.items,i=e.items,r=Y(n,i).prependedItemsCount;s.captureScroll(n,i,r)}}),z(this,"didUpdateState",function(e){var t=s.getState();if(s.onStateChange&&(function(e,t){if(E(e,t))return!0;if("object"!==L(e)||null===e||"object"!==L(t)||null===t)return!1;var n=Object.keys(e),i=Object.keys(t);if(n.length!==i.length)return!1;for(var r=0;r<n.length;r++)if(!M.call(t,n[r])||!E(e[n[r]],t[n[r]]))return!1;return!0}(t,e)||s.onStateChange(t,e)),e&&s.isRendered){R("~ Rendered ~"),t.firstShownItemIndex===e.firstShownItemIndex&&t.lastShownItemIndex===e.lastShownItemIndex&&t.items===e.items||s.onRendered();var n=e.items,i=t.items;if(i!==n){var r=Y(n,i),o=r.prependedItemsCount,a=r.appendedItemsCount;return o>0||a>0?o>0&&(s.itemHeights.onPrepend(o),void 0!==s.firstSeenItemIndex&&(s.firstSeenItemIndex+=o,s.lastSeenItemIndex+=o)):(s.itemHeights.initialize(),s.firstSeenItemIndex=void 0,s.lastSeenItemIndex=void 0),s.multiRenderLayout&&s.stopMultiRenderLayout(),s.onUpdateShownItemIndexes({reason:"update items",force:!0})}return s.resized?(s.resized=void 0,R("~ Rendered (resize) ~"),s.multiRenderLayout&&s.stopMultiRenderLayout(),s.onUpdateShownItemIndexes({reason:"resize"})):s.multiRenderLayout?s.onMultiRenderLayoutRendered():void 0}}),z(this,"updateShownItemIndexes",function(){var 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0!==s.latestLayoutVisibleAreaBottomAfterIncludingMargin&&s.getScrollY()+s.scrollableContainer.getHeight()>s.latestLayoutVisibleAreaBottomAfterIncludingMargin&&s.getState().lastShownItemIndex<s.getItemsCount()-1;if(R(n?"The user has scrolled far enough: force re-render":"The user hasn't scrolled too much: delay re-render"),!n)return s.onUserStopsScrollingTimeout=f(s.onUserStoppedScrolling,V)}R("~ Update layout (on ".concat(t,") ~")),s.updateShownItemIndexesRecursive()}}),z(this,"onUserStoppedScrolling",function(){s.isRendered&&s.updateLayout("stopped scrolling")});var l=a.getState,u=a.setState,h=a.onStateChange,d=a.customState,c=a.preserveScrollPositionAtBottomOnMount,m=a.shouldUpdateLayoutOnWindowResize,I=a.measureItemsBatchSize,p=a.getScrollableContainer,v=a.tbody,S=a.bypass,y=a.estimatedItemHeight,b=a.onItemInitialRender,w=a.onItemFirstRender,O=a.scrollableContainer,k=a.preserveScrollPositionOfTheBottomOfTheListOnMount,T=a.state;R("~ Initialize ~"),T&&(n=T.items),!O&&p&&(O=p()),O?this.scrollableContainer=new x(O):"undefined"!=typeof window&&(this.scrollableContainer=new C),v&&(R("~ <tbody/> detected ~"),this.tbody=!0,"undefined"!=typeof window&&window.document.documentMode&&(R("~ <tbody/> not supported ~"),"undefined"!=typeof window?setTimeout(function(){throw new Error(H)},0):console.error(H),S=!0)),S&&R('~ "bypass" mode ~'),this.bypass=S,this.initialItems=n,this.estimatedItemHeight=y,this.onStateChange=h,this._shouldUpdateLayoutOnWindowResize=m,this.measureItemsBatchSize=void 0===I?50:I,b?this.onItemFirstRender=b:w&&(this.onItemFirstRender=function(e){console.warn("[virtual-scroller] `onItemFirstRender(i)` is deprecated, use `onItemInitialRender(item)` instead.");var t=s.getState().items.indexOf(e);t>=0&&w(t)}),u?(this.getState=l,this.setState=function(e){return u(e,{willUpdateState:s.willUpdateState,didUpdateState:s.didUpdateState})}):(this.getState=function(){return s.state},this.setState=function(e){var t=s.getState(),n=U({},t,e);s.willUpdateState(n,t),s.state=n,s.didUpdateState(t)}),T&&R("Initial state (passed)",T),this.getContainerElement=t,t()&&function(e){for(;e.firstChild;)e.removeChild(e.firstChild)}(t()),this.itemHeights=new P(this.getContainerElement,this.getState),this.scrollableContainer&&(c&&(console.warn("[virtual-scroller] `preserveScrollPositionAtBottomOnMount` option/property has been renamed to `preserveScrollPositionOfTheBottomOfTheListOnMount`"),k=c),k&&(this.preserveScrollPositionOfTheBottomOfTheListOnMount={scrollableContainerContentHeight:this.scrollableContainer.getContentHeight()})),this.setState(T||this.getInitialState(d)),R("Items count",n.length),y&&R("Estimated item height",y)}var t,n,i;return t=e,(n=[{key:"getInitialState",value:function(e){var t=this.initialItems.length,n=U({},e,this.getInitialLayoutState(),{items:this.initialItems,itemStates:new Array(t)});return R("Initial state (autogenerated)",n),R("First shown item index",n.firstShownItemIndex),R("Last shown item index",n.lastShownItemIndex),n}},{key:"getInitialLayoutState",value:function(){var e,t,n=this.initialItems,i=n.length;return i>0&&(e=0,t=this.getLastShownItemIndex(e,i)),this.preserveScrollPositionOfTheBottomOfTheListOnMount&&(e=0,t=i-1),this.onBeforeShowItems(n,e,t),{itemHeights:new Array(i),itemSpacing:void 0,beforeItemsHeight:0,afterItemsHeight:0,firstShownItemIndex:e,lastShownItemIndex:t,scrollY:void 0}}},{key:"getEstimatedItemHeight",value:function(){return this.itemHeights&&this.itemHeights.getAverage()||this.estimatedItemHeight||0}},{key:"getItemSpacing",value:function(){return this.getState()&&this.getState().itemSpacing||0}},{key:"getEstimatedItemsCount",value:function(e){return this.getEstimatedItemHeight()?Math.ceil((e+this.getItemSpacing())/(this.getEstimatedItemHeight()+this.getItemSpacing())):1}},{key:"getEstimatedItemsCountOnScreen",value:function(){return this.scrollableContainer?this.getEstimatedItemsCount(2*this.getMargin()+this.scrollableContainer.getHeight()):1}},{key:"getLastShownItemIndex",value:function(e,t){return this.bypass?t-1:Math.min(e+(this.getEstimatedItemsCountOnScreen()-1),t-1)}},{key:"getItemsCount",value:function(){return this.getState().items.length}},{key:"getMargin",value:function(){return 1*this.scrollableContainer.getHeight()}},{key:"onBeforeShowItems",value:function(e,t,n){if(this.onItemFirstRender)if(void 0===this.firstSeenItemIndex){for(var i=t;i<=n;)this.onItemFirstRender(e[i]),i++;this.firstSeenItemIndex=t,this.lastSeenItemIndex=n}else{if(t<this.firstSeenItemIndex){for(var r=t,o=Math.min(n,this.firstSeenItemIndex-1),s=r;s<=o;)this.onItemFirstRender(e[s]),s++;this.firstSeenItemIndex=t}if(n>this.lastSeenItemIndex){for(var a=n,l=Math.max(t,this.lastSeenItemIndex+1);l<=a;)this.onItemFirstRender(e[l]),l++;this.lastSeenItemIndex=n}}}},{key:"onMount",value:function(){console.warn("[virtual-scroller] `.onMount()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"render",value:function(){console.warn("[virtual-scroller] `.render()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"listen",value:function(){if(!1===this.isRendered)throw new Error("[virtual-scroller] Can't restart a `VirtualScroller` after it has been stopped");R("~ Rendered (initial) 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var(--VirtualScroller-paddingBottom);\n\t\t\t}\n\t\t".replace(/[\n\t]/g,""),document.head.appendChild(t))}(this.getContainerElement()),this.preserveScrollPositionOfTheBottomOfTheListOnMount?this.scrollTo(0,this.getScrollY()+(this.scrollableContainer.getHeight()-this.preserveScrollPositionOfTheBottomOfTheListOnMount.scrollableContainerContentHeight)):this.onUpdateShownItemIndexes({reason:"mount"})}},{key:"onRendered",value:function(){this.updateItemHeights(),this.tbody&&this.updateTbodyPadding()}},{key:"scrollTo",value:function(e,t){this.scrollableContainer.scrollTo(e,t)}},{key:"getScrollY",value:function(){return this.scrollableContainer.getScrollY()}},{key:"getVisibleAreaBounds",value:function(){var e=this.getScrollY();return{top:e,bottom:e+this.scrollableContainer.getHeight()}}},{key:"getHeight",value:function(){return this.getContainerElement().getBoundingClientRect().height}},{key:"getTopOffset",value:function(){return this.scrollableContainer.getTopOffset(this.getContainerElement())}},{key:"shouldUpdateLayoutOnScrollableContainerResize",value:function(e){if(e&&e.target===window){if(document.fullscreenElement&&this.getContainerElement().contains(document.fullscreenElement))return!1;if(this._shouldUpdateLayoutOnWindowResize&&!this._shouldUpdateLayoutOnWindowResize(e))return!1}var t=this.scrollableContainerWidth,n=this.scrollableContainerHeight;return this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.scrollableContainerWidth===t?this.scrollableContainerHeight!==n&&"UPDATE_INDEXES":"UPDATE_LAYOUT"}},{key:"onUnmount",value:function(){console.warn("[virtual-scroller] `.onUnmount()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"destroy",value:function(){console.warn("[virtual-scroller] `.destroy()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"stop",value:function(){this.isRendered=!1,this.removeScrollPositionListener(),this.bypass||(this.removeScrollListener(),this.scrollableContainerUnlistenResize(),g(this.onUserStopsScrollingTimeout),g(this.watchContainerElementCoordinatesTimer))}},{key:"updateTbodyPadding",value:function(){var e=this.getState(),t=e.beforeItemsHeight,n=e.afterItemsHeight;!function(e,t,n){e.style.setProperty("--VirtualScroller-paddingTop",O(t)),e.style.setProperty("--VirtualScroller-paddingBottom",O(n))}(this.getContainerElement(),t,n)}},{key:"updateItemHeights",value:function(){var e=this.getState(),t=e.firstShownItemIndex,n=e.lastShownItemIndex,i=this.getState().firstShownItemIndex;void 0!==t&&(R("~ Measure item heights ~"),this.itemHeights.update(t,n,i),A()&&R("Item heights",this.getState().itemHeights.slice()))}},{key:"updateItemHeight",value:function(e){var 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r=this.getVisibleItemIndexes(e,t,n);if(void 0!==r.firstShownItemIndex)return r;R("Off-screen")}else R("Off-screen")}},{key:"getBeforeItemsHeight",value:function(e,t){for(var n=0,i=0;i<e;)n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),n+=this.getItemSpacing(),i++;return n}},{key:"getAfterItemsHeight",value:function(e,t){for(var n=0,i=t+1;i<this.getItemsCount();)n+=this.getItemSpacing(),n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),i++;return n}},{key:"updateWillBeHiddenItemHeightsAndState",value:function(e,t){for(var n=this.getState().firstShownItemIndex;n<=this.getState().lastShownItemIndex;)n>=e&&n<=t||this.updateItemHeight(n),n++}},{key:"watchContainerElementCoordinates",value:function(){var e=this,t=Date.now();!function n(){e.isRendered&&(void 0!==e.topOffset&&e.getTopOffset()!==e.topOffset&&e.onUpdateShownItemIndexes({reason:"top offset 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Array(d).concat(l))),c>0&&(R("Appended items count",c),u=u.concat(new Array(c)),l&&(l=l.concat(new Array(c)))),r+=d,o+=d,s+=this.itemHeights.getAverage()*d,a+=this.itemHeights.getAverage()*c):(R("Non-incremental items update"),R("Previous items",n),R("New items",e),u=new Array(e.length),l=new Array(e.length),0===e.length?(r=void 0,o=void 0):(r=0,o=this.getLastShownItemIndex(r,e.length)),s=0,a=0),R("First shown item index",r),R("Last shown item index",o),R("Before items height",s),R("After items height (actual or estimated)",a),this.onBeforeShowItems(e,r,o),this.preserveScrollPositionOnPrependItems=t.preserveScrollPositionOnPrependItems||t.preserveScrollPosition,this.setState({items:e,itemStates:l,itemHeights:u,firstShownItemIndex:r,lastShownItemIndex:o,beforeItemsHeight:s,afterItemsHeight:a})}},{key:"getItemElement",value:function(e){return this.getContainerElement().childNodes[e]}}])&&B(t.prototype,n),i&&B(t,i),e}();function Y(e,t){var n=-1,i=-1;return 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Object.getOwnPropertyDescriptor(n,e).enumerable}))),i.forEach(function(t){z(e,t,n[t])})}return e}function B(e,t){for(var n=0;n<t.length;n++){var i=t[n];i.enumerable=i.enumerable||!1,i.configurable=!0,"value"in i&&(i.writable=!0),Object.defineProperty(e,i.key,i)}}function z(e,t,n){return t in e?Object.defineProperty(e,t,{value:n,enumerable:!0,configurable:!0,writable:!0}):e[t]=n,e}var j=250,V=100,D=function(){function e(t,n){var i,r,o,s=this,a=arguments.length>2&&void 0!==arguments[2]?arguments[2]:{};!function(e,t){if(!(e instanceof t))throw new TypeError("Cannot call a class as a function")}(this,e),z(this,"updateLayout",function(){return s.onUpdateShownItemIndexes({reason:"manual"})}),z(this,"onScroll",function(){return s.onUpdateShownItemIndexes({reason:"scroll"})}),z(this,"restoreScrollPosition",function(){var e=s.getState().scrollY;void 0!==e&&s.scrollTo(0,e)}),z(this,"updateScrollPosition",function(){return s.getState().scrollY=s.getScrollY()}),z(this,"layout",function(){return s.updateLayout()}),z(this,"onResize",(i=function(e){if(s.isRendered){var t=s.shouldUpdateLayoutOnScrollableContainerResize(e);"UPDATE_LAYOUT"===t?(A("~ Scrollable container size changed, re-measure item heights. ~"),s.resized=!0,s.setState(s.getInitialLayoutState())):"UPDATE_INDEXES"===t&&s.onUpdateShownItemIndexes({reason:"resize"})}},r=j,function(){for(var e=this,t=arguments.length,n=new Array(t),s=0;s<t;s++)n[s]=arguments[s];clearTimeout(o),o=setTimeout(function(){return i.apply(e,n)},r)})),z(this,"willUpdateState",function(e,t){if(t&&s.preserveScrollPositionOnPrependItems){s.preserveScrollPositionOnPrependItems=void 0;var n=t.items,i=e.items,r=Y(n,i).prependedItemsCount;s.captureScroll(n,i,r)}}),z(this,"didUpdateState",function(e){var t=s.getState();if(s.onStateChange&&(function(e,t){if(E(e,t))return!0;if("object"!==L(e)||null===e||"object"!==L(t)||null===t)return!1;var n=Object.keys(e),i=Object.keys(t);if(n.length!==i.length)return!1;for(var r=0;r<n.length;r++)if(!M.call(t,n[r])||!E(e[n[r]],t[n[r]]))return!1;return!0}(t,e)||s.onStateChange(t,e)),e&&s.isRendered){A("~ Rendered ~"),t.firstShownItemIndex===e.firstShownItemIndex&&t.lastShownItemIndex===e.lastShownItemIndex&&t.items===e.items||s.onRendered();var n=e.items,i=t.items;if(i!==n){var r=Y(n,i),o=r.prependedItemsCount,a=r.appendedItemsCount;return o>0||a>0?o>0&&(s.itemHeights.onPrepend(o),void 0!==s.firstSeenItemIndex&&(s.firstSeenItemIndex+=o,s.lastSeenItemIndex+=o)):(s.itemHeights.initialize(),s.firstSeenItemIndex=void 0,s.lastSeenItemIndex=void 0),s.updateSeenItemIndexes(),s.multiRenderLayout&&s.stopMultiRenderLayout(),s.onUpdateShownItemIndexes({reason:"update items",force:!0})}return s.resized?(s.resized=void 0,A("~ Rendered (resize) ~"),s.multiRenderLayout&&s.stopMultiRenderLayout(),s.onUpdateShownItemIndexes({reason:"resize"})):s.multiRenderLayout?s.onMultiRenderLayoutRendered():void 0}}),z(this,"updateShownItemIndexes",function(){var e=s.getShownItemIndexes(),t=e.firstShownItemIndex,n=e.lastShownItemIndex,i=e.redoLayoutAfterRender,r=s.getBeforeItemsHeight(t,n),o=s.getAfterItemsHeight(t,n);s.updateWillBeHiddenItemHeightsAndState(t,n),A("~ Layout results "+(s.bypass?"(bypass) ":"")+"~"),A("First shown item index",t),A("Last shown item index",n),A("Before items height",r),A("After items height (actual or estimated)",o),A("Average item height (calculated on previous render)",s.itemHeights.getAverage()),R()&&(A("Item heights",s.getState().itemHeights.slice()),A("Item states",s.getState().itemStates.slice())),i&&(A("Schedule a re-layout after the upcoming rerender"),s.redoLayoutAfterRender=!0),void 0!==s.firstSeenItemIndex&&(t>s.lastSeenItemIndex+1||n<s.firstSeenItemIndex-1)&&(s.firstSeenItemIndex=void 0,s.lastSeenItemIndex=void 0),s.onBeforeShowItems(s.getState().items,t,n,s.firstSeenItemIndex,s.lastSeenItemIndex),s.setState({firstShownItemIndex:t,lastShownItemIndex:n,beforeItemsHeight:r,afterItemsHeight:o})}),z(this,"updateShownItemIndexesRecursive",function(){s.multiRenderLayout=!0,s.updateShownItemIndexes()}),z(this,"restoreScroll",function(){var e=s.restoreScrollAfterPrepend,t=e.index,n=e.visibleAreaTop;s.restoreScrollAfterPrepend=void 0;var i=s.getItemElement(t).getBoundingClientRect().top-n;0!==i&&(A("Restore scroll position: scroll by",i),s.scrollTo(0,s.getScrollY()+i))}),z(this,"onUpdateShownItemIndexes",function(e){var t=e.reason;e.force;if(0!==s.getItemsCount()&&!s.multiRenderLayout){if(g(s.onUserStopsScrollingTimeout),"scroll"===t){var n=void 0!==s.latestLayoutVisibleAreaTopAfterIncludingMargin&&s.getScrollY()<s.latestLayoutVisibleAreaTopAfterIncludingMargin&&s.getState().firstShownItemIndex>0||void 0!==s.latestLayoutVisibleAreaBottomAfterIncludingMargin&&s.getScrollY()+s.scrollableContainer.getHeight()>s.latestLayoutVisibleAreaBottomAfterIncludingMargin&&s.getState().lastShownItemIndex<s.getItemsCount()-1;if(A(n?"The user has scrolled far enough: force re-render":"The user hasn't scrolled too much: delay re-render"),!n)return s.onUserStopsScrollingTimeout=f(s.onUserStoppedScrolling,V)}A("~ Update layout (on ".concat(t,") ~")),s.updateShownItemIndexesRecursive()}}),z(this,"onUserStoppedScrolling",function(){s.isRendered&&s.updateLayout("stopped scrolling")});var l=a.getState,u=a.setState,h=a.onStateChange,d=a.customState,c=a.preserveScrollPositionAtBottomOnMount,m=a.shouldUpdateLayoutOnWindowResize,I=a.measureItemsBatchSize,p=a.getScrollableContainer,v=a.tbody,S=a.bypass,y=a.estimatedItemHeight,b=a.onItemInitialRender,w=a.onItemFirstRender,O=a.scrollableContainer,k=a.preserveScrollPositionOfTheBottomOfTheListOnMount,T=a.state;A("~ Initialize ~"),T&&(n=T.items),!O&&p&&(O=p()),O?this.scrollableContainer=new x(O):"undefined"!=typeof window&&(this.scrollableContainer=new C),v&&(A("~ <tbody/> detected ~"),this.tbody=!0,"undefined"!=typeof window&&window.document.documentMode&&(A("~ <tbody/> not supported ~"),"undefined"!=typeof window?setTimeout(function(){throw new Error(H)},0):console.error(H),S=!0)),S&&A('~ "bypass" mode ~'),this.bypass=S,this.initialItems=n,this.estimatedItemHeight=y,this.onStateChange=h,this._shouldUpdateLayoutOnWindowResize=m,this.measureItemsBatchSize=void 0===I?50:I,b?this.onItemFirstRender=b:w&&(this.onItemFirstRender=function(e){console.warn("[virtual-scroller] `onItemFirstRender(i)` is deprecated, use `onItemInitialRender(item)` instead.");var t=s.getState().items.indexOf(e);t>=0&&w(t)}),u?(this.getState=l,this.setState=function(e){return u(e,{willUpdateState:s.willUpdateState,didUpdateState:s.didUpdateState})}):(this.getState=function(){return s.state},this.setState=function(e){var t=s.getState(),n=U({},t,e);s.willUpdateState(n,t),s.state=n,s.didUpdateState(t)}),T&&A("Initial state (passed)",T),this.getContainerElement=t,t()&&function(e){for(;e.firstChild;)e.removeChild(e.firstChild)}(t()),this.itemHeights=new P(this.getContainerElement,this.getState),this.scrollableContainer&&(c&&(console.warn("[virtual-scroller] `preserveScrollPositionAtBottomOnMount` option/property has been renamed to `preserveScrollPositionOfTheBottomOfTheListOnMount`"),k=c),k&&(this.preserveScrollPositionOfTheBottomOfTheListOnMount={scrollableContainerContentHeight:this.scrollableContainer.getContentHeight()})),this.setState(T||this.getInitialState(d)),A("Items count",n.length),y&&A("Estimated item height",y)}var t,n,i;return t=e,(n=[{key:"getInitialState",value:function(e){var t=this.initialItems.length,n=U({},e,this.getInitialLayoutState(),{items:this.initialItems,itemStates:new Array(t)});return A("Initial state (autogenerated)",n),A("First shown item index",n.firstShownItemIndex),A("Last shown item index",n.lastShownItemIndex),n}},{key:"getInitialLayoutState",value:function(){var e,t,n=this.initialItems,i=n.length;return i>0&&(e=0,t=this.getLastShownItemIndex(e,i)),this.preserveScrollPositionOfTheBottomOfTheListOnMount&&(e=0,t=i-1),this.onBeforeShowItems(n,e,t,this.firstSeenItemIndex,this.lastSeenItemIndex),{itemHeights:new Array(i),itemSpacing:void 0,beforeItemsHeight:0,afterItemsHeight:0,firstShownItemIndex:e,lastShownItemIndex:t,scrollY:void 0}}},{key:"getEstimatedItemHeight",value:function(){return this.itemHeights&&this.itemHeights.getAverage()||this.estimatedItemHeight||0}},{key:"getItemSpacing",value:function(){return this.getState()&&this.getState().itemSpacing||0}},{key:"getEstimatedItemsCount",value:function(e){return this.getEstimatedItemHeight()?Math.ceil((e+this.getItemSpacing())/(this.getEstimatedItemHeight()+this.getItemSpacing())):1}},{key:"getEstimatedItemsCountOnScreen",value:function(){return this.scrollableContainer?this.getEstimatedItemsCount(2*this.getMargin()+this.scrollableContainer.getHeight()):1}},{key:"getLastShownItemIndex",value:function(e,t){return this.bypass?t-1:Math.min(e+(this.getEstimatedItemsCountOnScreen()-1),t-1)}},{key:"getItemsCount",value:function(){return this.getState().items.length}},{key:"getMargin",value:function(){return 1*this.scrollableContainer.getHeight()}},{key:"onBeforeShowItems",value:function(e,t,n,i,r){var o=this.onItemFirstRender;if(o)if(void 0===i)for(var s=t;s<=n;)o(e[s]),s++;else{if(t<i)for(var a=t,l=Math.min(n,i-1),u=a;u<=l;)o(e[u]),u++;if(n>r)for(var h=n,d=Math.max(t,r+1);d<=h;)o(e[d]),d++}}},{key:"updateSeenItemIndexes",value:function(){var e=this.firstSeenItemIndex,t=this.lastSeenItemIndex,n=this.getState(),i=n.firstShownItemIndex,r=n.lastShownItemIndex;void 0===e?(e=i,t=r):(i<e&&(e=i),r>t&&(t=r)),this.firstSeenItemIndex=e,this.lastSeenItemIndex=t}},{key:"onMount",value:function(){console.warn("[virtual-scroller] `.onMount()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"render",value:function(){console.warn("[virtual-scroller] `.render()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"listen",value:function(){if(!1===this.isRendered)throw new Error("[virtual-scroller] Can't restart a `VirtualScroller` after it has been stopped");A("~ Rendered (initial) ~"),this.isRendered=!0,this.onRendered(),this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.restoreScrollPosition(),this.updateScrollPosition(),this.removeScrollPositionListener=this.scrollableContainer.addScrollListener(this.updateScrollPosition),this.bypass||(this.removeScrollListener=this.scrollableContainer.addScrollListener(this.onScroll),this.scrollableContainerUnlistenResize=this.scrollableContainer.onResize(this.onResize)),this.tbody&&function(e){e.classList.add("VirtualScroller");var t=document.getElementById("VirtualScrollerStyle");t||((t=document.createElement("style")).id="VirtualScrollerStyle",t.innerText="\n\t\t\ttbody.VirtualScroller:before {\n\t\t\t\tcontent: '';\n\t\t\t\tdisplay: table-row;\n\t\t\t\theight: var(--VirtualScroller-paddingTop);\n\t\t\t}\n\t\t\ttbody.VirtualScroller:after {\n\t\t\t\tcontent: '';\n\t\t\t\tdisplay: table-row;\n\t\t\t\theight: var(--VirtualScroller-paddingBottom);\n\t\t\t}\n\t\t".replace(/[\n\t]/g,""),document.head.appendChild(t))}(this.getContainerElement()),this.preserveScrollPositionOfTheBottomOfTheListOnMount?this.scrollTo(0,this.getScrollY()+(this.scrollableContainer.getHeight()-this.preserveScrollPositionOfTheBottomOfTheListOnMount.scrollableContainerContentHeight)):this.onUpdateShownItemIndexes({reason:"mount"})}},{key:"onRendered",value:function(){this.updateItemHeights(),this.tbody&&this.updateTbodyPadding()}},{key:"scrollTo",value:function(e,t){this.scrollableContainer.scrollTo(e,t)}},{key:"getScrollY",value:function(){return this.scrollableContainer.getScrollY()}},{key:"getVisibleAreaBounds",value:function(){var e=this.getScrollY();return{top:e,bottom:e+this.scrollableContainer.getHeight()}}},{key:"getHeight",value:function(){return this.getContainerElement().getBoundingClientRect().height}},{key:"getTopOffset",value:function(){return this.scrollableContainer.getTopOffset(this.getContainerElement())}},{key:"shouldUpdateLayoutOnScrollableContainerResize",value:function(e){if(e&&e.target===window){if(document.fullscreenElement&&this.getContainerElement().contains(document.fullscreenElement))return!1;if(this._shouldUpdateLayoutOnWindowResize&&!this._shouldUpdateLayoutOnWindowResize(e))return!1}var t=this.scrollableContainerWidth,n=this.scrollableContainerHeight;return this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.scrollableContainerWidth===t?this.scrollableContainerHeight!==n&&"UPDATE_INDEXES":"UPDATE_LAYOUT"}},{key:"onUnmount",value:function(){console.warn("[virtual-scroller] `.onUnmount()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"destroy",value:function(){console.warn("[virtual-scroller] `.destroy()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"stop",value:function(){this.isRendered=!1,this.removeScrollPositionListener(),this.bypass||(this.removeScrollListener(),this.scrollableContainerUnlistenResize(),g(this.onUserStopsScrollingTimeout),g(this.watchContainerElementCoordinatesTimer))}},{key:"updateTbodyPadding",value:function(){var e=this.getState(),t=e.beforeItemsHeight,n=e.afterItemsHeight;!function(e,t,n){e.style.setProperty("--VirtualScroller-paddingTop",O(t)),e.style.setProperty("--VirtualScroller-paddingBottom",O(n))}(this.getContainerElement(),t,n)}},{key:"updateItemHeights",value:function(){var e=this.getState(),t=e.firstShownItemIndex,n=e.lastShownItemIndex,i=this.getState().firstShownItemIndex;void 0!==t&&(A("~ Measure item heights ~"),this.itemHeights.update(t,n,i),R()&&A("Item heights",this.getState().itemHeights.slice()))}},{key:"updateItemHeight",value:function(e){var t=this.getState().firstShownItemIndex;this.itemHeights.updateItemHeight(e,t)}},{key:"onItemStateChange",value:function(e,t){R()&&(A("~ Item state changed ~"),A("Item",e),A("Previous state\n"+JSON.stringify(this.getState().itemStates[e],null,2)),A("New state\n"+JSON.stringify(t,null,2))),this.getState().itemStates[e]=t}},{key:"onItemHeightChange",value:function(e){var t=this.getState().itemHeights,n=t[e];this.updateItemHeight(e);var i=t[e];n!==i&&(A("~ Item height changed ~"),A("Item",e),A("Previous height",n),A("New height",i),this.onUpdateShownItemIndexes({reason:"item height change"}))}},{key:"getItemCoordinates",value:function(e){for(var t=this.getTopOffset(),n=0;n<e;)t+=this.getState().itemHeights[n],t+=this.getItemSpacing(),n++;return{top:t,bottom:t+this.getState().itemHeights[e],height:this.getState().itemHeights[n]}}},{key:"getVisibleItemIndexes",value:function(e,t,n){for(var i,r,o,s=0,a=!1,l=0;l<this.getItemsCount();){var u=this.itemHeights.get(l);if(void 0===u){A("Item index ".concat(l,' lies within the visible area or its "margins", but its height hasn\'t been measured yet. Mark the item as "shown", render the list, measure the item\'s height and redo the layout.')),o=l,void 0===i&&(i=l);var h=t-(n+s);r=Math.min(l+(this.getEstimatedItemsCount(h)-1),this.getItemsCount()-1),a=!0;break}if(s+=u,void 0===i&&n+s>e&&(A("First visible item index",l),i=l),l<this.getItemsCount()-1&&(s+=this.getItemSpacing()),n+s>t){A("Last visible item index",l),void 0!==i&&(r=l);break}l++}return void 0!==i&&void 0===r&&A("Last item index (is fully visible)",r=this.getItemsCount()-1),this.restoreScrollAfterPrepend&&(r<this.restoreScrollAfterPrepend.index&&(r=this.restoreScrollAfterPrepend.index),a=!1),a&&this.measureItemsBatchSize&&(r=Math.min(r,o+this.measureItemsBatchSize-1)),{firstShownItemIndex:i,lastShownItemIndex:r,redoLayoutAfterRender:a}}},{key:"getOffscreenListShownItemIndexes",value:function(){return{firstShownItemIndex:0,lastShownItemIndex:0,redoLayoutAfterRender:void 0===this.itemHeights.get(0)}}},{key:"getItemIndexes",value:function(e,t,n,i){if(n+i>e&&n<t){var r=this.getVisibleItemIndexes(e,t,n);if(void 0!==r.firstShownItemIndex)return r;A("Off-screen")}else A("Off-screen")}},{key:"getBeforeItemsHeight",value:function(e,t){for(var n=0,i=0;i<e;)n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),n+=this.getItemSpacing(),i++;return n}},{key:"getAfterItemsHeight",value:function(e,t){for(var n=0,i=t+1;i<this.getItemsCount();)n+=this.getItemSpacing(),n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),i++;return n}},{key:"updateWillBeHiddenItemHeightsAndState",value:function(e,t){for(var n=this.getState().firstShownItemIndex;n<=this.getState().lastShownItemIndex;)n>=e&&n<=t||this.updateItemHeight(n),n++}},{key:"watchContainerElementCoordinates",value:function(){var e=this,t=Date.now();!function n(){e.isRendered&&(void 0!==e.topOffset&&e.getTopOffset()!==e.topOffset&&e.onUpdateShownItemIndexes({reason:"top offset change"}),Date.now()-t<3e3&&(e.watchContainerElementCoordinatesTimer=f(n,500)))}()}},{key:"getShownItemIndexes",value:function(){if(this.bypass)return{firstShownItemIndex:0,lastShownItemIndex:this.getItemsCount()-1};var e=this.getTopOffset();void 0===this.topOffset&&this.watchContainerElementCoordinates(),this.topOffset=e;var t=this.getVisibleAreaBounds(),n=t.top,i=t.bottom;return this.latestLayoutVisibleAreaTopAfterIncludingMargin=n-this.getMargin(),this.latestLayoutVisibleAreaBottomAfterIncludingMargin=i+this.getMargin(),this.getItemIndexes(n-this.getMargin(),i+this.getMargin(),e,this.getHeight())||this.getOffscreenListShownItemIndexes()}},{key:"onMultiRenderLayoutRendered",value:function(){var e=this;if(this.redoLayoutAfterRender)return this.redoLayoutAfterRender=void 0,f(function(){e.isRendered&&e.updateShownItemIndexesRecursive()},0);this.stopMultiRenderLayout()}},{key:"stopMultiRenderLayout",value:function(){this.multiRenderLayout=void 0,this.redoLayoutAfterRender||this.restoreScrollAfterPrepend&&this.restoreScroll()}},{key:"captureScroll",value:function(e,t,n){0!==e.length&&(void 0===n&&(n=t.indexOf(e[0])),n<0||0!==n&&(this.getState().firstShownItemIndex>0||this.restoreScrollAfterPrepend&&this.restoreScrollAfterPrepend.previousItems===e&&this.restoreScrollAfterPrepend.nextItems===t||(this.restoreScrollAfterPrepend={previousItems:e,nextItems:t,index:n,visibleAreaTop:this.getItemElement(0).getBoundingClientRect().top})))}},{key:"updateItems",value:function(e,t){return this.setItems(e,t)}},{key:"setItems",value:function(e){var t=arguments.length>1&&void 0!==arguments[1]?arguments[1]:{},n=this.getState().items,i=this.getState(),r=i.firstShownItemIndex,o=i.lastShownItemIndex,s=i.beforeItemsHeight,a=i.afterItemsHeight,l=i.itemStates,u=i.itemHeights,h=(i.itemSpacing,this.firstSeenItemIndex),d=this.lastSeenItemIndex;A("~ Update items ~");var c=Y(n,e),m=c.prependedItemsCount,f=c.appendedItemsCount;m>0||f>0?(m>0&&(A("Prepend",m,"items"),u=new Array(m).concat(u),l&&(l=new Array(m).concat(l))),f>0&&(A("Append",f,"items"),u=u.concat(new Array(f)),l&&(l=l.concat(new Array(f)))),r+=m,o+=m,void 0!==h&&(h+=m,d+=m),s+=this.itemHeights.getAverage()*m,a+=this.itemHeights.getAverage()*f):(A("Items have changed, and it's not a simple append and/or prepend: rerender the entire list from scratch."),A("Previous items",n),A("New items",e),h=void 0,d=void 0,u=new Array(e.length),l=new Array(e.length),0===e.length?(r=void 0,o=void 0):(r=0,o=this.getLastShownItemIndex(r,e.length)),s=0,a=0),A("First shown item index",r),A("Last shown item index",o),A("Before items height",s),A("After items height (actual or estimated)",a),this.onBeforeShowItems(e,r,o,h,d),this.preserveScrollPositionOnPrependItems=t.preserveScrollPositionOnPrependItems||t.preserveScrollPosition,this.setState({items:e,itemStates:l,itemHeights:u,firstShownItemIndex:r,lastShownItemIndex:o,beforeItemsHeight:s,afterItemsHeight:a})}},{key:"getItemElement",value:function(e){return this.getContainerElement().childNodes[e]}}])&&B(t.prototype,n),i&&B(t,i),e}();function Y(e,t){var n=-1,i=-1;return e.length>0&&(n=t.indexOf(e[0]))>=0&&function(e,t,n){var i=0;for(;i<e.length;){if(t.length<=n+i||t[n+i]!==e[i])return!1;i++}return!0}(e,t,n)&&(i=n+e.length-1),n>=0&&i>=0?{prependedItemsCount:n,appendedItemsCount:t.length-(i+1)}:{prependedItemsCount:-1,appendedItemsCount:-1}}function _(e,t){if(null==e)return{};var n,i,r=function(e,t){if(null==e)return{};var n,i,r={},o=Object.keys(e);for(i=0;i<o.length;i++)n=o[i],t.indexOf(n)>=0||(r[n]=e[n]);return r}(e,t);if(Object.getOwnPropertySymbols){var o=Object.getOwnPropertySymbols(e);for(i=0;i<o.length;i++)n=o[i],t.indexOf(n)>=0||Object.prototype.propertyIsEnumerable.call(e,n)&&(r[n]=e[n])}return r}function N(e,t){for(var n=0;n<t.length;n++){var i=t[n];i.enumerable=i.enumerable||!1,i.configurable=!0,"value"in i&&(i.writable=!0),Object.defineProperty(e,i.key,i)}}function W(e,t,n){return t in e?Object.defineProperty(e,t,{value:n,enumerable:!0,configurable:!0,writable:!0}):e[t]=n,e}return function(){function e(t,n,i){var r=this,o=arguments.length>3&&void 0!==arguments[3]?arguments[3]:{};!function(e,t){if(!(e instanceof t))throw new TypeError("Cannot call a class as a function")}(this,e),W(this,"onStateChange",function(e,t){var n=e.items,i=e.firstShownItemIndex,o=e.lastShownItemIndex,s=e.beforeItemsHeight,a=e.afterItemsHeight;A("~ On state change ~"),A("Previous state",t),A("New state",e),r.tbody||(r.container.style.paddingTop=O(s),r.container.style.paddingBottom=O(a));var l=t&&n===t.items&&n.length>0;if(l){A("Incremental rerender");for(var u=t.lastShownItemIndex;u>=t.firstShownItemIndex;)u>=i&&u<=o||(A("Remove item index",u),r.unmountItem(r.container.childNodes[u-t.firstShownItemIndex])),u--}else for(A("Rerender from scratch");r.container.firstChild;)r.unmountItem(r.container.firstChild);for(var h=l,d=h&&r.container.firstChild,c=i;c<=o;){if(l&&c>=t.firstShownItemIndex&&c<=t.lastShownItemIndex)h&&(h=!1);else{var m=r.renderItem(n[c]);h?(A("Prepend item index",c),r.container.insertBefore(m,d)):(A("Append item index",c),r.container.appendChild(m))}c++}}),W(this,"onUnmount",function(){console.warn("[virtual-scroller] `.onUnmount()` instance method name is deprecated, use `.stop()` instance method name instead."),r.stop()}),W(this,"destroy",function(){console.warn("[virtual-scroller] `.destroy()` instance method name is deprecated, use `.stop()` instance method name instead."),r.stop()}),W(this,"stop",function(){r.virtualScroller.stop()}),this.container=t,this.renderItem=i;var s=o.onMount,a=o.onItemUnmount,l=_(o,["onMount","onItemUnmount"]);this.onItemUnmount=a,this.tbody="TBODY"===this.container.tagName,this.virtualScroller=new D(function(){return r.container},n,function(e){for(var t=1;t<arguments.length;t++){var n=null!=arguments[t]?arguments[t]:{},i=Object.keys(n);"function"==typeof Object.getOwnPropertySymbols&&(i=i.concat(Object.getOwnPropertySymbols(n).filter(function(e){return Object.getOwnPropertyDescriptor(n,e).enumerable}))),i.forEach(function(t){W(e,t,n[t])})}return e}({},l,{tbody:this.tbody,onStateChange:this.onStateChange})),s&&s(),this.virtualScroller.listen()}var t,n,i;return t=e,(n=[{key:"unmountItem",value:function(e){this.container.removeChild(e),this.onItemUnmount&&this.onItemUnmount(e)}},{key:"onItemHeightChange",value:function(e){this.virtualScroller.onItemHeightChange(e)}},{key:"updateItems",value:function(e,t){this.setItems(e,t)}},{key:"setItems",value:function(e,t){this.virtualScroller.setItems(e,t)}},{key:"getItemCoordinates",value:function(e){return this.virtualScroller.getItemCoordinates(e)}}])&&N(t.prototype,n),i&&N(t,i),e}()});
 //# sourceMappingURL=virtual-scroller-dom.js.map

bundle/virtual-scroller-react.js

@@ -1,2 +0,2 @@
-!function(e,t){"object"==typeof exports&&"undefined"!=typeof module?module.exports=t(require("react"),require("prop-types")):"function"==typeof define&&define.amd?define(["react","prop-types"],t):(e=e||self).VirtualScroller=t(e.React,e.PropTypes)}(this,function(e,t){"use strict";e=e&&e.hasOwnProperty("default")?e.default:e,t=t&&t.hasOwnProperty("default")?t.default:t;var n="undefined"!=typeof globalThis?globalThis:"undefined"!=typeof window?window:"undefined"!=typeof global?global:"undefined"!=typeof self?self:{};for(var i,r=(function(e){(function(){var t,n,i,r,o,s;"undefined"!=typeof performance&&null!==performance&&performance.now?e.exports=function(){return performance.now()}:"undefined"!=typeof process&&null!==process&&process.hrtime?(e.exports=function(){return(t()-o)/1e6},n=process.hrtime,r=(t=function(){var e;return 1e9*(e=n())[0]+e[1]})(),s=1e9*process.uptime(),o=r-s):Date.now?(e.exports=function(){return Date.now()-i},i=Date.now()):(e.exports=function(){return(new Date).getTime()-i},i=(new Date).getTime())}).call(n)}(i={exports:{}},i.exports),i.exports),o="undefined"==typeof window?n:window,s=["moz","webkit"],a="AnimationFrame",l=o["request"+a],u=o["cancel"+a]||o["cancelRequest"+a],h=0;!l&&h<s.length;h++)l=o[s[h]+"Request"+a],u=o[s[h]+"Cancel"+a]||o[s[h]+"CancelRequest"+a];if(!l||!u){var d=0,c=0,m=[];l=function(e){if(0===m.length){var t=r(),n=Math.max(0,1e3/60-(t-d));d=n+t,setTimeout(function(){var e=m.slice(0);m.length=0;for(var t=0;t<e.length;t++)if(!e[t].cancelled)try{e[t].callback(d)}catch(e){setTimeout(function(){throw e},0)}},Math.round(n))}return m.push({handle:++c,callback:e,cancelled:!1}),c},u=function(e){for(var t=0;t<m.length;t++)m[t].handle===e&&(m[t].cancelled=!0)}}var f=function(e){return l.call(o,e)};f.cancel=function(){u.apply(o,arguments)},f.polyfill=function(e){e||(e=o),e.requestAnimationFrame=l,e.cancelAnimationFrame=u};var g=f.cancel;function p(e,t){var n=Date.now(),i=f(function r(){Date.now()-n>=t?e():i=f(r)});return{clear:function(){return g(i)}}}function I(e){e&&e.clear()}function S(e){return(S="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}function v(e,t){return!t||"object"!==S(t)&&"function"!=typeof t?function(e){if(void 0===e)throw new ReferenceError("this hasn't been initialised - 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See: https://gitlab.com/catamphetamine/virtual-scroller/-/issues/1";function k(e){return function(e){if(Array.isArray(e)){for(var t=0,n=new Array(e.length);t<e.length;t++)n[t]=e[t];return n}}(e)||function(e){if(Symbol.iterator in Object(e)||"[object Arguments]"===Object.prototype.toString.call(e))return Array.from(e)}(e)||function(){throw new TypeError("Invalid attempt to spread non-iterable instance")}()}function A(){if(T()){for(var e,t=arguments.length,n=new Array(t),i=0;i<t;i++)n[i]=arguments[i];(e=console).log.apply(e,k(["[virtual-scroller]"].concat(n)))}}function T(){return"undefined"!=typeof window&&window.VirtualScrollerDebug}function L(e,t){for(var n=0;n<t.length;n++){var i=t[n];i.enumerable=i.enumerable||!1,i.configurable=!0,"value"in i&&(i.writable=!0),Object.defineProperty(e,i.key,i)}}var M=function(){function e(t,n){!function(e,t){if(!(e instanceof t))throw new TypeError("Cannot call a class as a 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this.measuredItemsHeight?this.measuredItemsHeight/(this.lastMeasuredItemIndex-this.firstMeasuredItemIndex+1):0}},{key:"get",value:function(e){return this.getState().itemHeights[e]}},{key:"set",value:function(e,t){this.getState().itemHeights[e]=t}},{key:"onPrepend",value:function(e){void 0!==this.firstMeasuredItemIndex&&(this.firstMeasuredItemIndex+=e,this.lastMeasuredItemIndex+=e)}}])&&L(t.prototype,n),i&&L(t,i),e}();function U(e){return(U="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}var E=Object.prototype.hasOwnProperty;function B(e,t){return e===t?0!==e||0!==t||1/e==1/t:e!=e&&t!=t}function z(e){for(var t=1;t<arguments.length;t++){var n=null!=arguments[t]?arguments[t]:{},i=Object.keys(n);"function"==typeof Object.getOwnPropertySymbols&&(i=i.concat(Object.getOwnPropertySymbols(n).filter(function(e){return 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this.scrollableContainer?this.getEstimatedItemsCount(2*this.getMargin()+this.scrollableContainer.getHeight()):1}},{key:"getLastShownItemIndex",value:function(e,t){return this.bypass?t-1:Math.min(e+(this.getEstimatedItemsCountOnScreen()-1),t-1)}},{key:"getItemsCount",value:function(){return this.getState().items.length}},{key:"getMargin",value:function(){return 1*this.scrollableContainer.getHeight()}},{key:"onBeforeShowItems",value:function(e,t,n){if(this.onItemFirstRender)if(void 0===this.firstSeenItemIndex){for(var i=t;i<=n;)this.onItemFirstRender(e[i]),i++;this.firstSeenItemIndex=t,this.lastSeenItemIndex=n}else{if(t<this.firstSeenItemIndex){for(var r=t,o=Math.min(n,this.firstSeenItemIndex-1),s=r;s<=o;)this.onItemFirstRender(e[s]),s++;this.firstSeenItemIndex=t}if(n>this.lastSeenItemIndex){for(var a=n,l=Math.max(t,this.lastSeenItemIndex+1);l<=a;)this.onItemFirstRender(e[l]),l++;this.lastSeenItemIndex=n}}}},{key:"onMount",value:function(){console.warn("[virtual-scroller] `.onMount()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"render",value:function(){console.warn("[virtual-scroller] `.render()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"listen",value:function(){if(!1===this.isRendered)throw new Error("[virtual-scroller] Can't restart a `VirtualScroller` after it has been stopped");A("~ Rendered (initial) ~"),this.isRendered=!0,this.onRendered(),this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.restoreScrollPosition(),this.updateScrollPosition(),this.removeScrollPositionListener=this.scrollableContainer.addScrollListener(this.updateScrollPosition),this.bypass||(this.removeScrollListener=this.scrollableContainer.addScrollListener(this.onScroll),this.scrollableContainerUnlistenResize=this.scrollableContainer.onResize(this.onResize)),this.tbody&&function(e){e.classList.add("VirtualScroller");var t=document.getElementById("VirtualScrollerStyle");t||((t=document.createElement("style")).id="VirtualScrollerStyle",t.innerText="\n\t\t\ttbody.VirtualScroller:before {\n\t\t\t\tcontent: '';\n\t\t\t\tdisplay: table-row;\n\t\t\t\theight: var(--VirtualScroller-paddingTop);\n\t\t\t}\n\t\t\ttbody.VirtualScroller:after {\n\t\t\t\tcontent: '';\n\t\t\t\tdisplay: table-row;\n\t\t\t\theight: var(--VirtualScroller-paddingBottom);\n\t\t\t}\n\t\t".replace(/[\n\t]/g,""),document.head.appendChild(t))}(this.getContainerElement()),this.preserveScrollPositionOfTheBottomOfTheListOnMount?this.scrollTo(0,this.getScrollY()+(this.scrollableContainer.getHeight()-this.preserveScrollPositionOfTheBottomOfTheListOnMount.scrollableContainerContentHeight)):this.onUpdateShownItemIndexes({reason:"mount"})}},{key:"onRendered",value:function(){this.updateItemHeights(),this.tbody&&this.updateTbodyPadding()}},{key:"scrollTo",value:function(e,t){this.scrollableContainer.scrollTo(e,t)}},{key:"getScrollY",value:function(){return this.scrollableContainer.getScrollY()}},{key:"getVisibleAreaBounds",value:function(){var e=this.getScrollY();return{top:e,bottom:e+this.scrollableContainer.getHeight()}}},{key:"getHeight",value:function(){return this.getContainerElement().getBoundingClientRect().height}},{key:"getTopOffset",value:function(){return this.scrollableContainer.getTopOffset(this.getContainerElement())}},{key:"shouldUpdateLayoutOnScrollableContainerResize",value:function(e){if(e&&e.target===window){if(document.fullscreenElement&&this.getContainerElement().contains(document.fullscreenElement))return!1;if(this._shouldUpdateLayoutOnWindowResize&&!this._shouldUpdateLayoutOnWindowResize(e))return!1}var t=this.scrollableContainerWidth,n=this.scrollableContainerHeight;return this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.scrollableContainerWidth===t?this.scrollableContainerHeight!==n&&"UPDATE_INDEXES":"UPDATE_LAYOUT"}},{key:"onUnmount",value:function(){console.warn("[virtual-scroller] `.onUnmount()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"destroy",value:function(){console.warn("[virtual-scroller] `.destroy()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"stop",value:function(){this.isRendered=!1,this.removeScrollPositionListener(),this.bypass||(this.removeScrollListener(),this.scrollableContainerUnlistenResize(),I(this.onUserStopsScrollingTimeout),I(this.watchContainerElementCoordinatesTimer))}},{key:"updateTbodyPadding",value:function(){var e=this.getState(),t=e.beforeItemsHeight,n=e.afterItemsHeight;!function(e,t,n){e.style.setProperty("--VirtualScroller-paddingTop",H(t)),e.style.setProperty("--VirtualScroller-paddingBottom",H(n))}(this.getContainerElement(),t,n)}},{key:"updateItemHeights",value:function(){var e=this.getState(),t=e.firstShownItemIndex,n=e.lastShownItemIndex,i=this.getState().firstShownItemIndex;void 0!==t&&(A("~ Measure item heights ~"),this.itemHeights.update(t,n,i),T()&&A("Item heights",this.getState().itemHeights.slice()))}},{key:"updateItemHeight",value:function(e){var t=this.getState().firstShownItemIndex;this.itemHeights.updateItemHeight(e,t)}},{key:"onItemStateChange",value:function(e,t){T()&&(A("~ Item state changed ~"),A("Item",e),A("Previous state\n"+JSON.stringify(this.getState().itemStates[e],null,2)),A("New state\n"+JSON.stringify(t,null,2))),this.getState().itemStates[e]=t}},{key:"onItemHeightChange",value:function(e){var t=this.getState().itemHeights,n=t[e];this.updateItemHeight(e);var i=t[e];n!==i&&(A("~ Item height changed ~"),A("Item",e),A("Previous height",n),A("New height",i),this.onUpdateShownItemIndexes({reason:"item height change"}))}},{key:"getItemCoordinates",value:function(e){for(var t=this.getTopOffset(),n=0;n<e;)t+=this.getState().itemHeights[n],t+=this.getItemSpacing(),n++;return{top:t,bottom:t+this.getState().itemHeights[e],height:this.getState().itemHeights[n]}}},{key:"getVisibleItemIndexes",value:function(e,t,n){for(var i,r,o,s=0,a=!1,l=0;l<this.getItemsCount();){var u=this.itemHeights.get(l);if(void 0===u){A("Item index ".concat(l,' lies within the visible area or its "margins", but its height hasn\'t been measured yet. Mark the item as "shown", render the list, measure the item\'s height and redo the layout.')),o=l,void 0===i&&(i=l);var h=t-(n+s);r=Math.min(l+(this.getEstimatedItemsCount(h)-1),this.getItemsCount()-1),a=!0;break}if(s+=u,void 0===i&&n+s>e&&(A("First visible item index",l),i=l),l<this.getItemsCount()-1&&(s+=this.getItemSpacing()),n+s>t){A("Last visible item index",l),void 0!==i&&(r=l);break}l++}return void 0!==i&&void 0===r&&A("Last item index (is fully visible)",r=this.getItemsCount()-1),this.restoreScrollAfterPrepend&&(r<this.restoreScrollAfterPrepend.index&&(r=this.restoreScrollAfterPrepend.index),a=!1),a&&this.measureItemsBatchSize&&(r=Math.min(r,o+this.measureItemsBatchSize-1)),{firstShownItemIndex:i,lastShownItemIndex:r,redoLayoutAfterRender:a}}},{key:"getOffscreenListShownItemIndexes",value:function(){return{firstShownItemIndex:0,lastShownItemIndex:0,redoLayoutAfterRender:void 0===this.itemHeights.get(0)}}},{key:"getItemIndexes",value:function(e,t,n,i){if(n+i>e&&n<t){var r=this.getVisibleItemIndexes(e,t,n);if(void 0!==r.firstShownItemIndex)return r;A("Off-screen")}else A("Off-screen")}},{key:"getBeforeItemsHeight",value:function(e,t){for(var n=0,i=0;i<e;)n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),n+=this.getItemSpacing(),i++;return n}},{key:"getAfterItemsHeight",value:function(e,t){for(var n=0,i=t+1;i<this.getItemsCount();)n+=this.getItemSpacing(),n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),i++;return n}},{key:"updateWillBeHiddenItemHeightsAndState",value:function(e,t){for(var n=this.getState().firstShownItemIndex;n<=this.getState().lastShownItemIndex;)n>=e&&n<=t||this.updateItemHeight(n),n++}},{key:"watchContainerElementCoordinates",value:function(){var e=this,t=Date.now();!function n(){e.isRendered&&(void 0!==e.topOffset&&e.getTopOffset()!==e.topOffset&&e.onUpdateShownItemIndexes({reason:"top offset change"}),Date.now()-t<3e3&&(e.watchContainerElementCoordinatesTimer=p(n,500)))}()}},{key:"getShownItemIndexes",value:function(){if(this.bypass)return{firstShownItemIndex:0,lastShownItemIndex:this.getItemsCount()-1};var e=this.getTopOffset();void 0===this.topOffset&&this.watchContainerElementCoordinates(),this.topOffset=e;var t=this.getVisibleAreaBounds(),n=t.top,i=t.bottom;return this.latestLayoutVisibleAreaTopAfterIncludingMargin=n-this.getMargin(),this.latestLayoutVisibleAreaBottomAfterIncludingMargin=i+this.getMargin(),this.getItemIndexes(n-this.getMargin(),i+this.getMargin(),e,this.getHeight())||this.getOffscreenListShownItemIndexes()}},{key:"onMultiRenderLayoutRendered",value:function(){var e=this;if(this.redoLayoutAfterRender)return this.redoLayoutAfterRender=void 0,p(function(){e.isRendered&&e.updateShownItemIndexesRecursive()},0);this.stopMultiRenderLayout()}},{key:"stopMultiRenderLayout",value:function(){this.multiRenderLayout=void 0,this.redoLayoutAfterRender||this.restoreScrollAfterPrepend&&this.restoreScroll()}},{key:"captureScroll",value:function(e,t,n){0!==e.length&&(void 0===n&&(n=t.indexOf(e[0])),n<0||0!==n&&(this.getState().firstShownItemIndex>0||this.restoreScrollAfterPrepend&&this.restoreScrollAfterPrepend.previousItems===e&&this.restoreScrollAfterPrepend.nextItems===t||(this.restoreScrollAfterPrepend={previousItems:e,nextItems:t,index:n,visibleAreaTop:this.getItemElement(0).getBoundingClientRect().top})))}},{key:"updateItems",value:function(e,t){return this.setItems(e,t)}},{key:"setItems",value:function(e){var t=arguments.length>1&&void 0!==arguments[1]?arguments[1]:{},n=this.getState().items,i=this.getState(),r=i.firstShownItemIndex,o=i.lastShownItemIndex,s=i.beforeItemsHeight,a=i.afterItemsHeight,l=i.itemStates,u=i.itemHeights;i.itemSpacing;A("~ Update items ~");var h=F(n,e),d=h.prependedItemsCount,c=h.appendedItemsCount;d>0||c>0?(d>0&&(A("Prepended items count",d),u=new Array(d).concat(u),l&&(l=new Array(d).concat(l))),c>0&&(A("Appended items count",c),u=u.concat(new Array(c)),l&&(l=l.concat(new Array(c)))),r+=d,o+=d,s+=this.itemHeights.getAverage()*d,a+=this.itemHeights.getAverage()*c):(A("Non-incremental items update"),A("Previous items",n),A("New items",e),u=new Array(e.length),l=new Array(e.length),0===e.length?(r=void 0,o=void 0):(r=0,o=this.getLastShownItemIndex(r,e.length)),s=0,a=0),A("First shown item index",r),A("Last shown item index",o),A("Before items height",s),A("After items height (actual or estimated)",a),this.onBeforeShowItems(e,r,o),this.preserveScrollPositionOnPrependItems=t.preserveScrollPositionOnPrependItems||t.preserveScrollPosition,this.setState({items:e,itemStates:l,itemHeights:u,firstShownItemIndex:r,lastShownItemIndex:o,beforeItemsHeight:s,afterItemsHeight:a})}},{key:"getItemElement",value:function(e){return this.getContainerElement().childNodes[e]}}])&&j(t.prototype,n),i&&j(t,i),e}();function F(e,t){var n=-1,i=-1;return e.length>0&&(n=t.indexOf(e[0]))>=0&&function(e,t,n){var i=0;for(;i<e.length;){if(t.length<=n+i||t[n+i]!==e[i])return!1;i++}return!0}(e,t,n)&&(i=n+e.length-1),n>=0&&i>=0?{prependedItemsCount:n,appendedItemsCount:t.length-(i+1)}:{prependedItemsCount:-1,appendedItemsCount:-1}}function D(e){return(D="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}function N(){return(N=Object.assign||function(e){for(var t=1;t<arguments.length;t++){var n=arguments[t];for(var i in n)Object.prototype.hasOwnProperty.call(n,i)&&(e[i]=n[i])}return e}).apply(this,arguments)}function Y(e,t){if(null==e)return{};var n,i,r=function(e,t){if(null==e)return{};var n,i,r={},o=Object.keys(e);for(i=0;i<o.length;i++)n=o[i],t.indexOf(n)>=0||(r[n]=e[n]);return r}(e,t);if(Object.getOwnPropertySymbols){var o=Object.getOwnPropertySymbols(e);for(i=0;i<o.length;i++)n=o[i],t.indexOf(n)>=0||Object.prototype.propertyIsEnumerable.call(e,n)&&(r[n]=e[n])}return r}function J(e,t){for(var n=0;n<t.length;n++){var i=t[n];i.enumerable=i.enumerable||!1,i.configurable=!0,"value"in i&&(i.writable=!0),Object.defineProperty(e,i.key,i)}}function X(e){return(X=Object.setPrototypeOf?Object.getPrototypeOf:function(e){return e.__proto__||Object.getPrototypeOf(e)})(e)}function G(e){if(void 0===e)throw new ReferenceError("this hasn't been initialised - super() hasn't been called");return e}function K(e,t){return(K=Object.setPrototypeOf||function(e,t){return e.__proto__=t,e})(e,t)}function Q(e,t,n){return t in e?Object.defineProperty(e,t,{value:n,enumerable:!0,configurable:!0,writable:!0}):e[t]=n,e}var Z=t.elementType||t.oneOfType([t.string,t.func,t.object]),$=function(t){function n(t){var i,r,o;return function(e,t){if(!(e instanceof t))throw new TypeError("Cannot call a class as a function")}(this,n),r=this,o=X(n).call(this,t),i=!o||"object"!==D(o)&&"function"!=typeof o?G(r):o,Q(G(i),"container",e.createRef()),Q(G(i),"onItemStateChange",new Array(i.props.items.length)),Q(G(i),"onItemHeightChange",new Array(i.props.items.length)),Q(G(i),"itemRefs",new Array(i.props.items.length)),Q(G(i),"uniquePrefixes",[]),Q(G(i),"updateLayout",function(){return i.virtualScroller.updateLayout()}),Q(G(i),"layout",function(){return i.updateLayout()}),Q(G(i),"onItemInitialRender",function(){var e=i.props.onItemInitialRender;e&&e.apply(void 0,arguments)}),Q(G(i),"onItemFirstRender",function(){var e=i.props.onItemFirstRender;e&&e.apply(void 0,arguments)}),Q(G(i),"shouldUpdateLayoutOnWindowResize",function(){var e=i.props.shouldUpdateLayoutOnWindowResize;if(e)return e.apply(void 0,arguments)}),i.previousItemsProperty=t.items,i.generateUniquePrefix(),i.createVirtualScroller(),i}var i,r,o;return function(e,t){if("function"!=typeof t&&null!==t)throw new TypeError("Super expression must either be null or a function");e.prototype=Object.create(t&&t.prototype,{constructor:{value:e,writable:!0,configurable:!0}}),t&&K(e,t)}(n,e.Component),i=n,(r=[{key:"createVirtualScroller",value:function(){var e=this,t=this.props,n=t.as,i=t.items,r=t.initialState,o=t.initialCustomState,s=t.onStateChange,a=t.estimatedItemHeight,l=t.preserveScrollPositionOfTheBottomOfTheListOnMount,u=t.preserveScrollPositionAtBottomOnMount,h=t.measureItemsBatchSize,d=t.scrollableContainer,c=t.getScrollableContainer,m=t.bypass;this.virtualScroller=new q(function(){return e.container.current},i,{estimatedItemHeight:a,bypass:m,onItemInitialRender:this.onItemInitialRender,onItemFirstRender:this.onItemFirstRender,preserveScrollPositionOfTheBottomOfTheListOnMount:l,preserveScrollPositionAtBottomOnMount:u,shouldUpdateLayoutOnWindowResize:this.shouldUpdateLayoutOnWindowResize,measureItemsBatchSize:h,scrollableContainer:d,getScrollableContainer:c,tbody:"tbody"===n,state:r,customState:o,onStateChange:s,getState:function(){return e.state},setState:function(t,n){var i=n.willUpdateState,r=n.didUpdateState;e.willUpdateState=i,e.didUpdateState=r,e.state?e.setState(t):(i(t),e.state=t,r())}})}},{key:"shouldUseRefs",value:function(){var e,t=this.props.itemComponent;return(e=t).prototype&&e.prototype.isReactComponent}},{key:"getItemCoordinates",value:function(e){return this.virtualScroller.getItemCoordinates(e)}},{key:"updateItem",value:function(e){return this.renderItem(e)}},{key:"renderItem",value:function(e){var t=this;if(!this.shouldUseRefs())return console.error("[virtual-scroller] `.renderItem(i)` has been called but the `component` doesn't allow `ref`s. Only `component`s that're `React.Component`s support this feature.");if(this.itemRefs[e]&&this.itemRefs[e].current){var n=this.props.items,i=n[e];this.itemRefs[e].current.forceUpdate(function(){if(t._isMounted){var e=n.indexOf(i);e>=0&&t.virtualScroller.onItemHeightChange(e)}})}}},{key:"getItemRef",value:function(t){return this.itemRefs[t]||(this.itemRefs[t]=e.createRef()),this.itemRefs[t]}},{key:"getOnItemStateChange",value:function(e){var t=this;return this.onItemStateChange[e]||(this.onItemStateChange[e]=function(n){return t.virtualScroller.onItemStateChange(e,n)}),this.onItemStateChange[e]}},{key:"getOnItemHeightChange",value:function(e){var t=this;return this.onItemHeightChange[e]||(this.onItemHeightChange[e]=function(){return t.virtualScroller.onItemHeightChange(e)}),this.onItemHeightChange[e]}},{key:"generateUniquePrefix",value:function(){var e=String(Math.random()).slice(2);if(this.uniquePrefixes.indexOf(e)>=0)return this.generateUniquePrefix();this.uniquePrefixes.push(e),this.uniquePrefix=e}},{key:"componentDidMount",value:function(){var e=this.props.onMount;e&&e(),this._isMounted=!0,this.virtualScroller.listen()}},{key:"getSnapshotBeforeUpdate",value:function(e,t){return this.state!==t&&this.willUpdateState(this.state,t),null}},{key:"componentDidUpdate",value:function(e,t){this.state!==t&&this.didUpdateState(t);var n=this.props,i=n.items,r=n.preserveScrollPosition,o=n.preserveScrollPositionOnPrependItems;i!==e.items&&this.virtualScroller.setItems(i,{preserveScrollPositionOnPrependItems:o||r})}},{key:"componentWillUnmount",value:function(){this._isMounted=!1,this.virtualScroller.stop()}},{key:"render",value:function(){var t=this,n=this.props,i=n.as,r=n.itemComponent,o=n.itemComponentProps,s=(n.items,n.estimatedItemHeight,n.bypass,n.preserveScrollPositionOnPrependItems),a=n.preserveScrollPosition,l=(n.preserveScrollPositionOfTheBottomOfTheListOnMount,n.preserveScrollPositionAtBottomOnMount,n.shouldUpdateLayoutOnWindowResize,n.measureItemsBatchSize,n.scrollableContainer,n.getScrollableContainer,n.initialState,n.initialCustomState,n.onStateChange,n.onItemInitialRender,n.onItemFirstRender,n.onMount,n.className),u=Y(n,["as","itemComponent","itemComponentProps","items","estimatedItemHeight","bypass","preserveScrollPositionOnPrependItems","preserveScrollPosition","preserveScrollPositionOfTheBottomOfTheListOnMount","preserveScrollPositionAtBottomOnMount","shouldUpdateLayoutOnWindowResize","measureItemsBatchSize","scrollableContainer","getScrollableContainer","initialState","initialCustomState","onStateChange","onItemInitialRender","onItemFirstRender","onMount","className"]),h=this.virtualScroller.getState(),d=h.items,c=h.itemStates,m=h.firstShownItemIndex,f=h.lastShownItemIndex,g=h.beforeItemsHeight,p=h.afterItemsHeight,I=this.props.items,S=d;if(this.itemsPropertyWasChanged||(this.itemsPropertyWasChanged=this.props.items!==this.previousItemsProperty),this.previousItemsProperty=this.props.items,this.itemsPropertyWasChanged&&I!==S){var v=F(S,I),y=v.prependedItemsCount,b=v.appendedItemsCount;0===y&&b>0||((s||a)&&this.virtualScroller.captureScroll(S,I),this.generateUniquePrefix(),this.onItemStateChange=new Array(I.length),this.onItemHeightChange=new Array(I.length),this.itemRefs=new Array(I.length))}var w=this.virtualScroller.tbody;return e.createElement(i,N({},u,{ref:this.container,className:w?l?l+" VirtualScroller":"VirtualScroller":l,style:{paddingTop:w?void 0:H(g),paddingBottom:w?void 0:H(p)}}),d.map(function(n,i){return i>=m&&i<=f?e.createElement(r,N({},o,{ref:t.shouldUseRefs()?t.getItemRef(i):void 0,key:"".concat(t.uniquePrefix,":").concat(i),state:c&&c[i],onStateChange:t.getOnItemStateChange(i),onHeightChange:t.getOnItemHeightChange(i)}),n):null}))}}])&&J(i.prototype,r),o&&J(i,o),n}();return Q($,"propTypes",{as:Z,items:t.arrayOf(t.object).isRequired,itemComponent:Z.isRequired,itemComponentProps:t.object,estimatedItemHeight:t.number,bypass:t.bool,preserveScrollPositionOnPrependItems:t.bool,preserveScrollPosition:t.bool,preserveScrollPositionOfTheBottomOfTheListOnMount:t.bool,preserveScrollPositionAtBottomOnMount:t.bool,shouldUpdateLayoutOnWindowResize:t.func,measureItemsBatchSize:t.number,scrollableContainer:t.any,getScrollableContainer:t.func,className:t.string,onMount:t.func,onItemInitialRender:t.func,onItemFirstRender:t.func,onStateChange:t.func,initialCustomState:t.object,initialState:t.shape({items:t.arrayOf(t.object).isRequired,itemStates:t.arrayOf(t.any),firstShownItemIndex:t.number.isRequired,lastShownItemIndex:t.number.isRequired,beforeItemsHeight:t.number.isRequired,afterItemsHeight:t.number.isRequired,itemHeights:t.arrayOf(t.number).isRequired,itemSpacing:t.number})}),Q($,"defaultProps",{as:"div"}),$});
+!function(e,t){"object"==typeof exports&&"undefined"!=typeof module?module.exports=t(require("react"),require("prop-types")):"function"==typeof define&&define.amd?define(["react","prop-types"],t):(e=e||self).VirtualScroller=t(e.React,e.PropTypes)}(this,function(e,t){"use strict";e=e&&e.hasOwnProperty("default")?e.default:e,t=t&&t.hasOwnProperty("default")?t.default:t;var n="undefined"!=typeof globalThis?globalThis:"undefined"!=typeof window?window:"undefined"!=typeof global?global:"undefined"!=typeof self?self:{};for(var i,r=(function(e){(function(){var t,n,i,r,o,s;"undefined"!=typeof performance&&null!==performance&&performance.now?e.exports=function(){return performance.now()}:"undefined"!=typeof process&&null!==process&&process.hrtime?(e.exports=function(){return(t()-o)/1e6},n=process.hrtime,r=(t=function(){var e;return 1e9*(e=n())[0]+e[1]})(),s=1e9*process.uptime(),o=r-s):Date.now?(e.exports=function(){return Date.now()-i},i=Date.now()):(e.exports=function(){return(new Date).getTime()-i},i=(new Date).getTime())}).call(n)}(i={exports:{}},i.exports),i.exports),o="undefined"==typeof window?n:window,s=["moz","webkit"],a="AnimationFrame",l=o["request"+a],u=o["cancel"+a]||o["cancelRequest"+a],h=0;!l&&h<s.length;h++)l=o[s[h]+"Request"+a],u=o[s[h]+"Cancel"+a]||o[s[h]+"CancelRequest"+a];if(!l||!u){var d=0,c=0,m=[];l=function(e){if(0===m.length){var t=r(),n=Math.max(0,1e3/60-(t-d));d=n+t,setTimeout(function(){var e=m.slice(0);m.length=0;for(var t=0;t<e.length;t++)if(!e[t].cancelled)try{e[t].callback(d)}catch(e){setTimeout(function(){throw e},0)}},Math.round(n))}return m.push({handle:++c,callback:e,cancelled:!1}),c},u=function(e){for(var t=0;t<m.length;t++)m[t].handle===e&&(m[t].cancelled=!0)}}var f=function(e){return l.call(o,e)};f.cancel=function(){u.apply(o,arguments)},f.polyfill=function(e){e||(e=o),e.requestAnimationFrame=l,e.cancelAnimationFrame=u};var g=f.cancel;function p(e,t){var n=Date.now(),i=f(function r(){Date.now()-n>=t?e():i=f(r)});return{clear:function(){return g(i)}}}function I(e){e&&e.clear()}function S(e){return(S="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}function v(e,t){return!t||"object"!==S(t)&&"function"!=typeof t?function(e){if(void 0===e)throw new ReferenceError("this hasn't been initialised - 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See: https://gitlab.com/catamphetamine/virtual-scroller/-/issues/1";function k(e){return function(e){if(Array.isArray(e)){for(var t=0,n=new Array(e.length);t<e.length;t++)n[t]=e[t];return n}}(e)||function(e){if(Symbol.iterator in Object(e)||"[object Arguments]"===Object.prototype.toString.call(e))return Array.from(e)}(e)||function(){throw new TypeError("Invalid attempt to spread non-iterable instance")}()}function A(){if(T()){for(var e,t=arguments.length,n=new Array(t),i=0;i<t;i++)n[i]=arguments[i];(e=console).log.apply(e,k(["[virtual-scroller]"].concat(n)))}}function T(){return"undefined"!=typeof window&&window.VirtualScrollerDebug}function L(e,t){for(var n=0;n<t.length;n++){var i=t[n];i.enumerable=i.enumerable||!1,i.configurable=!0,"value"in i&&(i.writable=!0),Object.defineProperty(e,i.key,i)}}var M=function(){function e(t,n){!function(e,t){if(!(e instanceof t))throw new TypeError("Cannot call a class as a 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t=e.childNodes[0],n=e.childNodes[1],i=t.getBoundingClientRect(),r=n.getBoundingClientRect().top-(i.top+i.height);return window.VirtualScrollerDebug&&A("Measure item spacing",r),r}}},{key:"update",value:function(e,t,n){void 0===this.getState().itemSpacing&&(this.getState().itemSpacing=this.getItemSpacing()),void 0!==this.firstMeasuredItemIndex&&(e>this.lastMeasuredItemIndex+1||t<this.firstMeasuredItemIndex-1)&&this.reset();for(var i=this.firstMeasuredItemIndex,r=this.lastMeasuredItemIndex,o=!1,s=e;s<=t;){var a=this._getItemHeight(s,n);void 0!==a&&(this.set(s,a),(void 0===i||s<i)&&(this.measuredItemsHeight+=a,o||(this.firstMeasuredItemIndex=s,o=!0)),(void 0===r||s>r)&&(void 0!==r&&(this.measuredItemsHeight+=a),this.lastMeasuredItemIndex=s)),s++}}},{key:"updateItemHeight",value:function(e,t){var n=this.get(e),i=this._getItemHeight(e,t);void 0!==n&&void 0!==i&&(this.set(e,i),this.measuredItemsHeight+=i-n)}},{key:"getAverage",value:function(){return this.measuredItemsHeight?this.measuredItemsHeight/(this.lastMeasuredItemIndex-this.firstMeasuredItemIndex+1):0}},{key:"get",value:function(e){return this.getState().itemHeights[e]}},{key:"set",value:function(e,t){this.getState().itemHeights[e]=t}},{key:"onPrepend",value:function(e){void 0!==this.firstMeasuredItemIndex&&(this.firstMeasuredItemIndex+=e,this.lastMeasuredItemIndex+=e)}}])&&L(t.prototype,n),i&&L(t,i),e}();function U(e){return(U="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}var E=Object.prototype.hasOwnProperty;function B(e,t){return e===t?0!==e||0!==t||1/e==1/t:e!=e&&t!=t}function z(e){for(var t=1;t<arguments.length;t++){var n=null!=arguments[t]?arguments[t]:{},i=Object.keys(n);"function"==typeof Object.getOwnPropertySymbols&&(i=i.concat(Object.getOwnPropertySymbols(n).filter(function(e){return 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r=0;r<n.length;r++)if(!E.call(t,n[r])||!B(e[n[r]],t[n[r]]))return!1;return!0}(t,e)||s.onStateChange(t,e)),e&&s.isRendered){A("~ Rendered ~"),t.firstShownItemIndex===e.firstShownItemIndex&&t.lastShownItemIndex===e.lastShownItemIndex&&t.items===e.items||s.onRendered();var n=e.items,i=t.items;if(i!==n){var r=D(n,i),o=r.prependedItemsCount,a=r.appendedItemsCount;return o>0||a>0?o>0&&(s.itemHeights.onPrepend(o),void 0!==s.firstSeenItemIndex&&(s.firstSeenItemIndex+=o,s.lastSeenItemIndex+=o)):(s.itemHeights.initialize(),s.firstSeenItemIndex=void 0,s.lastSeenItemIndex=void 0),s.updateSeenItemIndexes(),s.multiRenderLayout&&s.stopMultiRenderLayout(),s.onUpdateShownItemIndexes({reason:"update items",force:!0})}return s.resized?(s.resized=void 0,A("~ Rendered (resize) ~"),s.multiRenderLayout&&s.stopMultiRenderLayout(),s.onUpdateShownItemIndexes({reason:"resize"})):s.multiRenderLayout?s.onMultiRenderLayoutRendered():void 0}}),_(this,"updateShownItemIndexes",function(){var e=s.getShownItemIndexes(),t=e.firstShownItemIndex,n=e.lastShownItemIndex,i=e.redoLayoutAfterRender,r=s.getBeforeItemsHeight(t,n),o=s.getAfterItemsHeight(t,n);s.updateWillBeHiddenItemHeightsAndState(t,n),A("~ Layout results "+(s.bypass?"(bypass) ":"")+"~"),A("First shown item index",t),A("Last shown item index",n),A("Before items height",r),A("After items height (actual or estimated)",o),A("Average item height (calculated on previous render)",s.itemHeights.getAverage()),T()&&(A("Item heights",s.getState().itemHeights.slice()),A("Item states",s.getState().itemStates.slice())),i&&(A("Schedule a re-layout after the upcoming rerender"),s.redoLayoutAfterRender=!0),void 0!==s.firstSeenItemIndex&&(t>s.lastSeenItemIndex+1||n<s.firstSeenItemIndex-1)&&(s.firstSeenItemIndex=void 0,s.lastSeenItemIndex=void 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t=s.getState(),n=z({},t,e);s.willUpdateState(n,t),s.state=n,s.didUpdateState(t)}),H&&A("Initial state (passed)",H),this.getContainerElement=t,t()&&function(e){for(;e.firstChild;)e.removeChild(e.firstChild)}(t()),this.itemHeights=new M(this.getContainerElement,this.getState),this.scrollableContainer&&(c&&(console.warn("[virtual-scroller] `preserveScrollPositionAtBottomOnMount` option/property has been renamed to `preserveScrollPositionOfTheBottomOfTheListOnMount`"),x=c),x&&(this.preserveScrollPositionOfTheBottomOfTheListOnMount={scrollableContainerContentHeight:this.scrollableContainer.getContentHeight()})),this.setState(H||this.getInitialState(d)),A("Items count",n.length),y&&A("Estimated item height",y)}var t,n,i;return t=e,(n=[{key:"getInitialState",value:function(e){var t=this.initialItems.length,n=z({},e,this.getInitialLayoutState(),{items:this.initialItems,itemStates:new Array(t)});return A("Initial state (autogenerated)",n),A("First shown item index",n.firstShownItemIndex),A("Last shown item index",n.lastShownItemIndex),n}},{key:"getInitialLayoutState",value:function(){var e,t,n=this.initialItems,i=n.length;return i>0&&(e=0,t=this.getLastShownItemIndex(e,i)),this.preserveScrollPositionOfTheBottomOfTheListOnMount&&(e=0,t=i-1),this.onBeforeShowItems(n,e,t,this.firstSeenItemIndex,this.lastSeenItemIndex),{itemHeights:new Array(i),itemSpacing:void 0,beforeItemsHeight:0,afterItemsHeight:0,firstShownItemIndex:e,lastShownItemIndex:t,scrollY:void 0}}},{key:"getEstimatedItemHeight",value:function(){return this.itemHeights&&this.itemHeights.getAverage()||this.estimatedItemHeight||0}},{key:"getItemSpacing",value:function(){return this.getState()&&this.getState().itemSpacing||0}},{key:"getEstimatedItemsCount",value:function(e){return this.getEstimatedItemHeight()?Math.ceil((e+this.getItemSpacing())/(this.getEstimatedItemHeight()+this.getItemSpacing())):1}},{key:"getEstimatedItemsCountOnScreen",value:function(){return this.scrollableContainer?this.getEstimatedItemsCount(2*this.getMargin()+this.scrollableContainer.getHeight()):1}},{key:"getLastShownItemIndex",value:function(e,t){return this.bypass?t-1:Math.min(e+(this.getEstimatedItemsCountOnScreen()-1),t-1)}},{key:"getItemsCount",value:function(){return this.getState().items.length}},{key:"getMargin",value:function(){return 1*this.scrollableContainer.getHeight()}},{key:"onBeforeShowItems",value:function(e,t,n,i,r){var o=this.onItemFirstRender;if(o)if(void 0===i)for(var s=t;s<=n;)o(e[s]),s++;else{if(t<i)for(var a=t,l=Math.min(n,i-1),u=a;u<=l;)o(e[u]),u++;if(n>r)for(var h=n,d=Math.max(t,r+1);d<=h;)o(e[d]),d++}}},{key:"updateSeenItemIndexes",value:function(){var e=this.firstSeenItemIndex,t=this.lastSeenItemIndex,n=this.getState(),i=n.firstShownItemIndex,r=n.lastShownItemIndex;void 0===e?(e=i,t=r):(i<e&&(e=i),r>t&&(t=r)),this.firstSeenItemIndex=e,this.lastSeenItemIndex=t}},{key:"onMount",value:function(){console.warn("[virtual-scroller] `.onMount()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"render",value:function(){console.warn("[virtual-scroller] `.render()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"listen",value:function(){if(!1===this.isRendered)throw new Error("[virtual-scroller] Can't restart a `VirtualScroller` after it has been stopped");A("~ Rendered (initial) ~"),this.isRendered=!0,this.onRendered(),this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.restoreScrollPosition(),this.updateScrollPosition(),this.removeScrollPositionListener=this.scrollableContainer.addScrollListener(this.updateScrollPosition),this.bypass||(this.removeScrollListener=this.scrollableContainer.addScrollListener(this.onScroll),this.scrollableContainerUnlistenResize=this.scrollableContainer.onResize(this.onResize)),this.tbody&&function(e){e.classList.add("VirtualScroller");var t=document.getElementById("VirtualScrollerStyle");t||((t=document.createElement("style")).id="VirtualScrollerStyle",t.innerText="\n\t\t\ttbody.VirtualScroller:before {\n\t\t\t\tcontent: '';\n\t\t\t\tdisplay: table-row;\n\t\t\t\theight: var(--VirtualScroller-paddingTop);\n\t\t\t}\n\t\t\ttbody.VirtualScroller:after {\n\t\t\t\tcontent: '';\n\t\t\t\tdisplay: table-row;\n\t\t\t\theight: var(--VirtualScroller-paddingBottom);\n\t\t\t}\n\t\t".replace(/[\n\t]/g,""),document.head.appendChild(t))}(this.getContainerElement()),this.preserveScrollPositionOfTheBottomOfTheListOnMount?this.scrollTo(0,this.getScrollY()+(this.scrollableContainer.getHeight()-this.preserveScrollPositionOfTheBottomOfTheListOnMount.scrollableContainerContentHeight)):this.onUpdateShownItemIndexes({reason:"mount"})}},{key:"onRendered",value:function(){this.updateItemHeights(),this.tbody&&this.updateTbodyPadding()}},{key:"scrollTo",value:function(e,t){this.scrollableContainer.scrollTo(e,t)}},{key:"getScrollY",value:function(){return this.scrollableContainer.getScrollY()}},{key:"getVisibleAreaBounds",value:function(){var e=this.getScrollY();return{top:e,bottom:e+this.scrollableContainer.getHeight()}}},{key:"getHeight",value:function(){return this.getContainerElement().getBoundingClientRect().height}},{key:"getTopOffset",value:function(){return this.scrollableContainer.getTopOffset(this.getContainerElement())}},{key:"shouldUpdateLayoutOnScrollableContainerResize",value:function(e){if(e&&e.target===window){if(document.fullscreenElement&&this.getContainerElement().contains(document.fullscreenElement))return!1;if(this._shouldUpdateLayoutOnWindowResize&&!this._shouldUpdateLayoutOnWindowResize(e))return!1}var t=this.scrollableContainerWidth,n=this.scrollableContainerHeight;return this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.scrollableContainerWidth===t?this.scrollableContainerHeight!==n&&"UPDATE_INDEXES":"UPDATE_LAYOUT"}},{key:"onUnmount",value:function(){console.warn("[virtual-scroller] `.onUnmount()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"destroy",value:function(){console.warn("[virtual-scroller] `.destroy()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"stop",value:function(){this.isRendered=!1,this.removeScrollPositionListener(),this.bypass||(this.removeScrollListener(),this.scrollableContainerUnlistenResize(),I(this.onUserStopsScrollingTimeout),I(this.watchContainerElementCoordinatesTimer))}},{key:"updateTbodyPadding",value:function(){var e=this.getState(),t=e.beforeItemsHeight,n=e.afterItemsHeight;!function(e,t,n){e.style.setProperty("--VirtualScroller-paddingTop",H(t)),e.style.setProperty("--VirtualScroller-paddingBottom",H(n))}(this.getContainerElement(),t,n)}},{key:"updateItemHeights",value:function(){var e=this.getState(),t=e.firstShownItemIndex,n=e.lastShownItemIndex,i=this.getState().firstShownItemIndex;void 0!==t&&(A("~ Measure item heights ~"),this.itemHeights.update(t,n,i),T()&&A("Item heights",this.getState().itemHeights.slice()))}},{key:"updateItemHeight",value:function(e){var t=this.getState().firstShownItemIndex;this.itemHeights.updateItemHeight(e,t)}},{key:"onItemStateChange",value:function(e,t){T()&&(A("~ Item state changed ~"),A("Item",e),A("Previous state\n"+JSON.stringify(this.getState().itemStates[e],null,2)),A("New state\n"+JSON.stringify(t,null,2))),this.getState().itemStates[e]=t}},{key:"onItemHeightChange",value:function(e){var t=this.getState().itemHeights,n=t[e];this.updateItemHeight(e);var i=t[e];n!==i&&(A("~ Item height changed ~"),A("Item",e),A("Previous height",n),A("New height",i),this.onUpdateShownItemIndexes({reason:"item height change"}))}},{key:"getItemCoordinates",value:function(e){for(var t=this.getTopOffset(),n=0;n<e;)t+=this.getState().itemHeights[n],t+=this.getItemSpacing(),n++;return{top:t,bottom:t+this.getState().itemHeights[e],height:this.getState().itemHeights[n]}}},{key:"getVisibleItemIndexes",value:function(e,t,n){for(var i,r,o,s=0,a=!1,l=0;l<this.getItemsCount();){var u=this.itemHeights.get(l);if(void 0===u){A("Item index ".concat(l,' lies within the visible area or its "margins", but its height hasn\'t been measured yet. Mark the item as "shown", render the list, measure the item\'s height and redo the layout.')),o=l,void 0===i&&(i=l);var h=t-(n+s);r=Math.min(l+(this.getEstimatedItemsCount(h)-1),this.getItemsCount()-1),a=!0;break}if(s+=u,void 0===i&&n+s>e&&(A("First visible item index",l),i=l),l<this.getItemsCount()-1&&(s+=this.getItemSpacing()),n+s>t){A("Last visible item index",l),void 0!==i&&(r=l);break}l++}return void 0!==i&&void 0===r&&A("Last item index (is fully visible)",r=this.getItemsCount()-1),this.restoreScrollAfterPrepend&&(r<this.restoreScrollAfterPrepend.index&&(r=this.restoreScrollAfterPrepend.index),a=!1),a&&this.measureItemsBatchSize&&(r=Math.min(r,o+this.measureItemsBatchSize-1)),{firstShownItemIndex:i,lastShownItemIndex:r,redoLayoutAfterRender:a}}},{key:"getOffscreenListShownItemIndexes",value:function(){return{firstShownItemIndex:0,lastShownItemIndex:0,redoLayoutAfterRender:void 0===this.itemHeights.get(0)}}},{key:"getItemIndexes",value:function(e,t,n,i){if(n+i>e&&n<t){var r=this.getVisibleItemIndexes(e,t,n);if(void 0!==r.firstShownItemIndex)return r;A("Off-screen")}else A("Off-screen")}},{key:"getBeforeItemsHeight",value:function(e,t){for(var n=0,i=0;i<e;)n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),n+=this.getItemSpacing(),i++;return n}},{key:"getAfterItemsHeight",value:function(e,t){for(var n=0,i=t+1;i<this.getItemsCount();)n+=this.getItemSpacing(),n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),i++;return n}},{key:"updateWillBeHiddenItemHeightsAndState",value:function(e,t){for(var n=this.getState().firstShownItemIndex;n<=this.getState().lastShownItemIndex;)n>=e&&n<=t||this.updateItemHeight(n),n++}},{key:"watchContainerElementCoordinates",value:function(){var e=this,t=Date.now();!function n(){e.isRendered&&(void 0!==e.topOffset&&e.getTopOffset()!==e.topOffset&&e.onUpdateShownItemIndexes({reason:"top offset change"}),Date.now()-t<3e3&&(e.watchContainerElementCoordinatesTimer=p(n,500)))}()}},{key:"getShownItemIndexes",value:function(){if(this.bypass)return{firstShownItemIndex:0,lastShownItemIndex:this.getItemsCount()-1};var e=this.getTopOffset();void 0===this.topOffset&&this.watchContainerElementCoordinates(),this.topOffset=e;var t=this.getVisibleAreaBounds(),n=t.top,i=t.bottom;return this.latestLayoutVisibleAreaTopAfterIncludingMargin=n-this.getMargin(),this.latestLayoutVisibleAreaBottomAfterIncludingMargin=i+this.getMargin(),this.getItemIndexes(n-this.getMargin(),i+this.getMargin(),e,this.getHeight())||this.getOffscreenListShownItemIndexes()}},{key:"onMultiRenderLayoutRendered",value:function(){var e=this;if(this.redoLayoutAfterRender)return this.redoLayoutAfterRender=void 0,p(function(){e.isRendered&&e.updateShownItemIndexesRecursive()},0);this.stopMultiRenderLayout()}},{key:"stopMultiRenderLayout",value:function(){this.multiRenderLayout=void 0,this.redoLayoutAfterRender||this.restoreScrollAfterPrepend&&this.restoreScroll()}},{key:"captureScroll",value:function(e,t,n){0!==e.length&&(void 0===n&&(n=t.indexOf(e[0])),n<0||0!==n&&(this.getState().firstShownItemIndex>0||this.restoreScrollAfterPrepend&&this.restoreScrollAfterPrepend.previousItems===e&&this.restoreScrollAfterPrepend.nextItems===t||(this.restoreScrollAfterPrepend={previousItems:e,nextItems:t,index:n,visibleAreaTop:this.getItemElement(0).getBoundingClientRect().top})))}},{key:"updateItems",value:function(e,t){return this.setItems(e,t)}},{key:"setItems",value:function(e){var t=arguments.length>1&&void 0!==arguments[1]?arguments[1]:{},n=this.getState().items,i=this.getState(),r=i.firstShownItemIndex,o=i.lastShownItemIndex,s=i.beforeItemsHeight,a=i.afterItemsHeight,l=i.itemStates,u=i.itemHeights,h=(i.itemSpacing,this.firstSeenItemIndex),d=this.lastSeenItemIndex;A("~ Update items ~");var c=D(n,e),m=c.prependedItemsCount,f=c.appendedItemsCount;m>0||f>0?(m>0&&(A("Prepend",m,"items"),u=new Array(m).concat(u),l&&(l=new Array(m).concat(l))),f>0&&(A("Append",f,"items"),u=u.concat(new Array(f)),l&&(l=l.concat(new Array(f)))),r+=m,o+=m,void 0!==h&&(h+=m,d+=m),s+=this.itemHeights.getAverage()*m,a+=this.itemHeights.getAverage()*f):(A("Items have changed, and it's not a simple append and/or prepend: rerender the entire list from scratch."),A("Previous items",n),A("New items",e),h=void 0,d=void 0,u=new Array(e.length),l=new Array(e.length),0===e.length?(r=void 0,o=void 0):(r=0,o=this.getLastShownItemIndex(r,e.length)),s=0,a=0),A("First shown item index",r),A("Last shown item index",o),A("Before items height",s),A("After items height (actual or estimated)",a),this.onBeforeShowItems(e,r,o,h,d),this.preserveScrollPositionOnPrependItems=t.preserveScrollPositionOnPrependItems||t.preserveScrollPosition,this.setState({items:e,itemStates:l,itemHeights:u,firstShownItemIndex:r,lastShownItemIndex:o,beforeItemsHeight:s,afterItemsHeight:a})}},{key:"getItemElement",value:function(e){return this.getContainerElement().childNodes[e]}}])&&j(t.prototype,n),i&&j(t,i),e}();function D(e,t){var n=-1,i=-1;return e.length>0&&(n=t.indexOf(e[0]))>=0&&function(e,t,n){var i=0;for(;i<e.length;){if(t.length<=n+i||t[n+i]!==e[i])return!1;i++}return!0}(e,t,n)&&(i=n+e.length-1),n>=0&&i>=0?{prependedItemsCount:n,appendedItemsCount:t.length-(i+1)}:{prependedItemsCount:-1,appendedItemsCount:-1}}function F(e){return(F="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}function Y(){return(Y=Object.assign||function(e){for(var t=1;t<arguments.length;t++){var n=arguments[t];for(var i in n)Object.prototype.hasOwnProperty.call(n,i)&&(e[i]=n[i])}return e}).apply(this,arguments)}function N(e,t){if(null==e)return{};var n,i,r=function(e,t){if(null==e)return{};var n,i,r={},o=Object.keys(e);for(i=0;i<o.length;i++)n=o[i],t.indexOf(n)>=0||(r[n]=e[n]);return r}(e,t);if(Object.getOwnPropertySymbols){var o=Object.getOwnPropertySymbols(e);for(i=0;i<o.length;i++)n=o[i],t.indexOf(n)>=0||Object.prototype.propertyIsEnumerable.call(e,n)&&(r[n]=e[n])}return r}function J(e,t){for(var n=0;n<t.length;n++){var i=t[n];i.enumerable=i.enumerable||!1,i.configurable=!0,"value"in i&&(i.writable=!0),Object.defineProperty(e,i.key,i)}}function X(e){return(X=Object.setPrototypeOf?Object.getPrototypeOf:function(e){return e.__proto__||Object.getPrototypeOf(e)})(e)}function G(e){if(void 0===e)throw new ReferenceError("this hasn't been initialised - super() hasn't been called");return e}function K(e,t){return(K=Object.setPrototypeOf||function(e,t){return e.__proto__=t,e})(e,t)}function Q(e,t,n){return t in e?Object.defineProperty(e,t,{value:n,enumerable:!0,configurable:!0,writable:!0}):e[t]=n,e}var Z=t.elementType||t.oneOfType([t.string,t.func,t.object]),$=function(t){function n(t){var i,r,o;return function(e,t){if(!(e instanceof t))throw new TypeError("Cannot call a class as a function")}(this,n),r=this,o=X(n).call(this,t),i=!o||"object"!==F(o)&&"function"!=typeof o?G(r):o,Q(G(i),"container",e.createRef()),Q(G(i),"onItemStateChange",new Array(i.props.items.length)),Q(G(i),"onItemHeightChange",new Array(i.props.items.length)),Q(G(i),"itemRefs",new Array(i.props.items.length)),Q(G(i),"uniquePrefixes",[]),Q(G(i),"updateLayout",function(){return i.virtualScroller.updateLayout()}),Q(G(i),"layout",function(){return i.updateLayout()}),Q(G(i),"onItemInitialRender",function(){var e=i.props.onItemInitialRender;e&&e.apply(void 0,arguments)}),Q(G(i),"onItemFirstRender",function(){var e=i.props.onItemFirstRender;e&&e.apply(void 0,arguments)}),Q(G(i),"shouldUpdateLayoutOnWindowResize",function(){var e=i.props.shouldUpdateLayoutOnWindowResize;if(e)return e.apply(void 0,arguments)}),i.previousItemsProperty=t.items,i.generateUniquePrefix(),i.createVirtualScroller(),i}var i,r,o;return function(e,t){if("function"!=typeof t&&null!==t)throw new TypeError("Super expression must either be null or a function");e.prototype=Object.create(t&&t.prototype,{constructor:{value:e,writable:!0,configurable:!0}}),t&&K(e,t)}(n,e.Component),i=n,(r=[{key:"createVirtualScroller",value:function(){var e=this,t=this.props,n=t.as,i=t.items,r=t.initialState,o=t.initialCustomState,s=t.onStateChange,a=t.estimatedItemHeight,l=t.preserveScrollPositionOfTheBottomOfTheListOnMount,u=t.preserveScrollPositionAtBottomOnMount,h=t.measureItemsBatchSize,d=t.scrollableContainer,c=t.getScrollableContainer,m=t.bypass;this.virtualScroller=new q(function(){return e.container.current},i,{estimatedItemHeight:a,bypass:m,onItemInitialRender:this.onItemInitialRender,onItemFirstRender:this.onItemFirstRender,preserveScrollPositionOfTheBottomOfTheListOnMount:l,preserveScrollPositionAtBottomOnMount:u,shouldUpdateLayoutOnWindowResize:this.shouldUpdateLayoutOnWindowResize,measureItemsBatchSize:h,scrollableContainer:d,getScrollableContainer:c,tbody:"tbody"===n,state:r,customState:o,onStateChange:s,getState:function(){return e.state},setState:function(t,n){var i=n.willUpdateState,r=n.didUpdateState;e.willUpdateState=i,e.didUpdateState=r,e.state?e.setState(t):(i(t),e.state=t,r())}})}},{key:"shouldUseRefs",value:function(){var e,t=this.props.itemComponent;return(e=t).prototype&&e.prototype.isReactComponent}},{key:"getItemCoordinates",value:function(e){return this.virtualScroller.getItemCoordinates(e)}},{key:"updateItem",value:function(e){return this.renderItem(e)}},{key:"renderItem",value:function(e){var t=this;if(!this.shouldUseRefs())return console.error("[virtual-scroller] `.renderItem(i)` has been called but the `component` doesn't allow `ref`s. Only `component`s that're `React.Component`s support this feature.");if(this.itemRefs[e]&&this.itemRefs[e].current){var n=this.props.items,i=n[e];this.itemRefs[e].current.forceUpdate(function(){if(t._isMounted){var e=n.indexOf(i);e>=0&&t.virtualScroller.onItemHeightChange(e)}})}}},{key:"getItemRef",value:function(t){return this.itemRefs[t]||(this.itemRefs[t]=e.createRef()),this.itemRefs[t]}},{key:"getOnItemStateChange",value:function(e){var t=this;return this.onItemStateChange[e]||(this.onItemStateChange[e]=function(n){return t.virtualScroller.onItemStateChange(e,n)}),this.onItemStateChange[e]}},{key:"getOnItemHeightChange",value:function(e){var t=this;return this.onItemHeightChange[e]||(this.onItemHeightChange[e]=function(){return t.virtualScroller.onItemHeightChange(e)}),this.onItemHeightChange[e]}},{key:"generateUniquePrefix",value:function(){var e=String(Math.random()).slice(2);if(this.uniquePrefixes.indexOf(e)>=0)return this.generateUniquePrefix();this.uniquePrefixes.push(e),this.uniquePrefix=e}},{key:"componentDidMount",value:function(){var e=this.props.onMount;e&&e(),this._isMounted=!0,this.virtualScroller.listen()}},{key:"getSnapshotBeforeUpdate",value:function(e,t){return this.state!==t&&this.willUpdateState(this.state,t),null}},{key:"componentDidUpdate",value:function(e,t){this.state!==t&&this.didUpdateState(t);var n=this.props,i=n.items,r=n.preserveScrollPosition,o=n.preserveScrollPositionOnPrependItems;i!==e.items&&this.virtualScroller.setItems(i,{preserveScrollPositionOnPrependItems:o||r})}},{key:"componentWillUnmount",value:function(){this._isMounted=!1,this.virtualScroller.stop()}},{key:"render",value:function(){var t=this,n=this.props,i=n.as,r=n.itemComponent,o=n.itemComponentProps,s=(n.items,n.estimatedItemHeight,n.bypass,n.preserveScrollPositionOnPrependItems),a=n.preserveScrollPosition,l=(n.preserveScrollPositionOfTheBottomOfTheListOnMount,n.preserveScrollPositionAtBottomOnMount,n.shouldUpdateLayoutOnWindowResize,n.measureItemsBatchSize,n.scrollableContainer,n.getScrollableContainer,n.initialState,n.initialCustomState,n.onStateChange,n.onItemInitialRender,n.onItemFirstRender,n.onMount,n.className),u=N(n,["as","itemComponent","itemComponentProps","items","estimatedItemHeight","bypass","preserveScrollPositionOnPrependItems","preserveScrollPosition","preserveScrollPositionOfTheBottomOfTheListOnMount","preserveScrollPositionAtBottomOnMount","shouldUpdateLayoutOnWindowResize","measureItemsBatchSize","scrollableContainer","getScrollableContainer","initialState","initialCustomState","onStateChange","onItemInitialRender","onItemFirstRender","onMount","className"]),h=this.virtualScroller.getState(),d=h.items,c=h.itemStates,m=h.firstShownItemIndex,f=h.lastShownItemIndex,g=h.beforeItemsHeight,p=h.afterItemsHeight,I=this.props.items,S=d;if(this.itemsPropertyWasChanged||(this.itemsPropertyWasChanged=this.props.items!==this.previousItemsProperty),this.previousItemsProperty=this.props.items,this.itemsPropertyWasChanged&&I!==S){var v=D(S,I),y=v.prependedItemsCount,b=v.appendedItemsCount;0===y&&b>0||((s||a)&&this.virtualScroller.captureScroll(S,I),this.generateUniquePrefix(),this.onItemStateChange=new Array(I.length),this.onItemHeightChange=new Array(I.length),this.itemRefs=new Array(I.length))}var w=this.virtualScroller.tbody;return e.createElement(i,Y({},u,{ref:this.container,className:w?l?l+" VirtualScroller":"VirtualScroller":l,style:{paddingTop:w?void 0:H(g),paddingBottom:w?void 0:H(p)}}),d.map(function(n,i){return i>=m&&i<=f?e.createElement(r,Y({},o,{ref:t.shouldUseRefs()?t.getItemRef(i):void 0,key:"".concat(t.uniquePrefix,":").concat(i),state:c&&c[i],onStateChange:t.getOnItemStateChange(i),onHeightChange:t.getOnItemHeightChange(i)}),n):null}))}}])&&J(i.prototype,r),o&&J(i,o),n}();return Q($,"propTypes",{as:Z,items:t.arrayOf(t.object).isRequired,itemComponent:Z.isRequired,itemComponentProps:t.object,estimatedItemHeight:t.number,bypass:t.bool,preserveScrollPositionOnPrependItems:t.bool,preserveScrollPosition:t.bool,preserveScrollPositionOfTheBottomOfTheListOnMount:t.bool,preserveScrollPositionAtBottomOnMount:t.bool,shouldUpdateLayoutOnWindowResize:t.func,measureItemsBatchSize:t.number,scrollableContainer:t.any,getScrollableContainer:t.func,className:t.string,onMount:t.func,onItemInitialRender:t.func,onItemFirstRender:t.func,onStateChange:t.func,initialCustomState:t.object,initialState:t.shape({items:t.arrayOf(t.object).isRequired,itemStates:t.arrayOf(t.any),firstShownItemIndex:t.number.isRequired,lastShownItemIndex:t.number.isRequired,beforeItemsHeight:t.number.isRequired,afterItemsHeight:t.number.isRequired,itemHeights:t.arrayOf(t.number).isRequired,itemSpacing:t.number})}),Q($,"defaultProps",{as:"div"}),$});
 //# sourceMappingURL=virtual-scroller-react.js.map

bundle/virtual-scroller.js

@@ -1,2 +0,2 @@
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t=s.getState(),n=U({},t,e);s.willUpdateState(n,t),s.state=n,s.didUpdateState(t)}),L&&R("Initial state (passed)",L),this.getContainerElement=t,t()&&function(e){for(;e.firstChild;)e.removeChild(e.firstChild)}(t()),this.itemHeights=new T(this.getContainerElement,this.getState),this.scrollableContainer&&(c&&(console.warn("[virtual-scroller] `preserveScrollPositionAtBottomOnMount` option/property has been renamed to `preserveScrollPositionOfTheBottomOfTheListOnMount`"),O=c),O&&(this.preserveScrollPositionOfTheBottomOfTheListOnMount={scrollableContainerContentHeight:this.scrollableContainer.getContentHeight()})),this.setState(L||this.getInitialState(d)),R("Items count",n.length),y&&R("Estimated item height",y)}var t,n,i;return t=e,(n=[{key:"getInitialState",value:function(e){var t=this.initialItems.length,n=U({},e,this.getInitialLayoutState(),{items:this.initialItems,itemStates:new Array(t)});return R("Initial state (autogenerated)",n),R("First shown item 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instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"render",value:function(){console.warn("[virtual-scroller] `.render()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"listen",value:function(){if(!1===this.isRendered)throw new Error("[virtual-scroller] Can't restart a `VirtualScroller` after it has been stopped");R("~ Rendered (initial) 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var(--VirtualScroller-paddingBottom);\n\t\t\t}\n\t\t".replace(/[\n\t]/g,""),document.head.appendChild(t))}(this.getContainerElement()),this.preserveScrollPositionOfTheBottomOfTheListOnMount?this.scrollTo(0,this.getScrollY()+(this.scrollableContainer.getHeight()-this.preserveScrollPositionOfTheBottomOfTheListOnMount.scrollableContainerContentHeight)):this.onUpdateShownItemIndexes({reason:"mount"})}},{key:"onRendered",value:function(){this.updateItemHeights(),this.tbody&&this.updateTbodyPadding()}},{key:"scrollTo",value:function(e,t){this.scrollableContainer.scrollTo(e,t)}},{key:"getScrollY",value:function(){return this.scrollableContainer.getScrollY()}},{key:"getVisibleAreaBounds",value:function(){var e=this.getScrollY();return{top:e,bottom:e+this.scrollableContainer.getHeight()}}},{key:"getHeight",value:function(){return this.getContainerElement().getBoundingClientRect().height}},{key:"getTopOffset",value:function(){return this.scrollableContainer.getTopOffset(this.getContainerElement())}},{key:"shouldUpdateLayoutOnScrollableContainerResize",value:function(e){if(e&&e.target===window){if(document.fullscreenElement&&this.getContainerElement().contains(document.fullscreenElement))return!1;if(this._shouldUpdateLayoutOnWindowResize&&!this._shouldUpdateLayoutOnWindowResize(e))return!1}var t=this.scrollableContainerWidth,n=this.scrollableContainerHeight;return this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.scrollableContainerWidth===t?this.scrollableContainerHeight!==n&&"UPDATE_INDEXES":"UPDATE_LAYOUT"}},{key:"onUnmount",value:function(){console.warn("[virtual-scroller] `.onUnmount()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"destroy",value:function(){console.warn("[virtual-scroller] `.destroy()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"stop",value:function(){this.isRendered=!1,this.removeScrollPositionListener(),this.bypass||(this.removeScrollListener(),this.scrollableContainerUnlistenResize(),g(this.onUserStopsScrollingTimeout),g(this.watchContainerElementCoordinatesTimer))}},{key:"updateTbodyPadding",value:function(){var e=this.getState(),t=e.beforeItemsHeight,n=e.afterItemsHeight;!function(e,t,n){e.style.setProperty("--VirtualScroller-paddingTop",H(t)),e.style.setProperty("--VirtualScroller-paddingBottom",H(n))}(this.getContainerElement(),t,n)}},{key:"updateItemHeights",value:function(){var e=this.getState(),t=e.firstShownItemIndex,n=e.lastShownItemIndex,i=this.getState().firstShownItemIndex;void 0!==t&&(R("~ Measure item heights ~"),this.itemHeights.update(t,n,i),A()&&R("Item heights",this.getState().itemHeights.slice()))}},{key:"updateItemHeight",value:function(e){var t=this.getState().firstShownItemIndex;this.itemHeights.updateItemHeight(e,t)}},{key:"onItemStateChange",value:function(e,t){A()&&(R("~ Item state changed ~"),R("Item",e),R("Previous state\n"+JSON.stringify(this.getState().itemStates[e],null,2)),R("New state\n"+JSON.stringify(t,null,2))),this.getState().itemStates[e]=t}},{key:"onItemHeightChange",value:function(e){var t=this.getState().itemHeights,n=t[e];this.updateItemHeight(e);var i=t[e];n!==i&&(R("~ Item height changed ~"),R("Item",e),R("Previous height",n),R("New height",i),this.onUpdateShownItemIndexes({reason:"item height change"}))}},{key:"getItemCoordinates",value:function(e){for(var t=this.getTopOffset(),n=0;n<e;)t+=this.getState().itemHeights[n],t+=this.getItemSpacing(),n++;return{top:t,bottom:t+this.getState().itemHeights[e],height:this.getState().itemHeights[n]}}},{key:"getVisibleItemIndexes",value:function(e,t,n){for(var i,r,o,s=0,a=!1,l=0;l<this.getItemsCount();){var u=this.itemHeights.get(l);if(void 0===u){R("Item index 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re-layout after the upcoming rerender"),s.redoLayoutAfterRender=!0),void 0!==s.firstSeenItemIndex&&(t>s.lastSeenItemIndex+1||n<s.firstSeenItemIndex-1)&&(s.firstSeenItemIndex=void 0,s.lastSeenItemIndex=void 0),s.onBeforeShowItems(s.getState().items,t,n,s.firstSeenItemIndex,s.lastSeenItemIndex),s.setState({firstShownItemIndex:t,lastShownItemIndex:n,beforeItemsHeight:r,afterItemsHeight:o})}),z(this,"updateShownItemIndexesRecursive",function(){s.multiRenderLayout=!0,s.updateShownItemIndexes()}),z(this,"restoreScroll",function(){var e=s.restoreScrollAfterPrepend,t=e.index,n=e.visibleAreaTop;s.restoreScrollAfterPrepend=void 0;var i=s.getItemElement(t).getBoundingClientRect().top-n;0!==i&&(A("Restore scroll position: scroll by",i),s.scrollTo(0,s.getScrollY()+i))}),z(this,"onUpdateShownItemIndexes",function(e){var t=e.reason;e.force;if(0!==s.getItemsCount()&&!s.multiRenderLayout){if(g(s.onUserStopsScrollingTimeout),"scroll"===t){var n=void 0!==s.latestLayoutVisibleAreaTopAfterIncludingMargin&&s.getScrollY()<s.latestLayoutVisibleAreaTopAfterIncludingMargin&&s.getState().firstShownItemIndex>0||void 0!==s.latestLayoutVisibleAreaBottomAfterIncludingMargin&&s.getScrollY()+s.scrollableContainer.getHeight()>s.latestLayoutVisibleAreaBottomAfterIncludingMargin&&s.getState().lastShownItemIndex<s.getItemsCount()-1;if(A(n?"The user has scrolled far enough: force re-render":"The user hasn't scrolled too much: delay re-render"),!n)return s.onUserStopsScrollingTimeout=f(s.onUserStoppedScrolling,j)}A("~ Update layout (on ".concat(t,") ~")),s.updateShownItemIndexesRecursive()}}),z(this,"onUserStoppedScrolling",function(){s.isRendered&&s.updateLayout("stopped scrolling")});var l=a.getState,u=a.setState,h=a.onStateChange,d=a.customState,c=a.preserveScrollPositionAtBottomOnMount,m=a.shouldUpdateLayoutOnWindowResize,I=a.measureItemsBatchSize,p=a.getScrollableContainer,v=a.tbody,S=a.bypass,y=a.estimatedItemHeight,w=a.onItemInitialRender,b=a.onItemFirstRender,H=a.scrollableContainer,O=a.preserveScrollPositionOfTheBottomOfTheListOnMount,L=a.state;A("~ Initialize ~"),L&&(n=L.items),!H&&p&&(H=p()),H?this.scrollableContainer=new x(H):"undefined"!=typeof window&&(this.scrollableContainer=new C),v&&(A("~ <tbody/> detected ~"),this.tbody=!0,"undefined"!=typeof window&&window.document.documentMode&&(A("~ <tbody/> not supported ~"),"undefined"!=typeof window?setTimeout(function(){throw new Error(k)},0):console.error(k),S=!0)),S&&A('~ "bypass" mode ~'),this.bypass=S,this.initialItems=n,this.estimatedItemHeight=y,this.onStateChange=h,this._shouldUpdateLayoutOnWindowResize=m,this.measureItemsBatchSize=void 0===I?50:I,w?this.onItemFirstRender=w:b&&(this.onItemFirstRender=function(e){console.warn("[virtual-scroller] `onItemFirstRender(i)` is deprecated, use `onItemInitialRender(item)` instead.");var t=s.getState().items.indexOf(e);t>=0&&b(t)}),u?(this.getState=l,this.setState=function(e){return u(e,{willUpdateState:s.willUpdateState,didUpdateState:s.didUpdateState})}):(this.getState=function(){return s.state},this.setState=function(e){var t=s.getState(),n=U({},t,e);s.willUpdateState(n,t),s.state=n,s.didUpdateState(t)}),L&&A("Initial state (passed)",L),this.getContainerElement=t,t()&&function(e){for(;e.firstChild;)e.removeChild(e.firstChild)}(t()),this.itemHeights=new T(this.getContainerElement,this.getState),this.scrollableContainer&&(c&&(console.warn("[virtual-scroller] `preserveScrollPositionAtBottomOnMount` option/property has been renamed to `preserveScrollPositionOfTheBottomOfTheListOnMount`"),O=c),O&&(this.preserveScrollPositionOfTheBottomOfTheListOnMount={scrollableContainerContentHeight:this.scrollableContainer.getContentHeight()})),this.setState(L||this.getInitialState(d)),A("Items count",n.length),y&&A("Estimated item height",y)}var t,n,i;return t=e,(n=[{key:"getInitialState",value:function(e){var t=this.initialItems.length,n=U({},e,this.getInitialLayoutState(),{items:this.initialItems,itemStates:new Array(t)});return A("Initial state (autogenerated)",n),A("First shown item index",n.firstShownItemIndex),A("Last shown item index",n.lastShownItemIndex),n}},{key:"getInitialLayoutState",value:function(){var e,t,n=this.initialItems,i=n.length;return i>0&&(e=0,t=this.getLastShownItemIndex(e,i)),this.preserveScrollPositionOfTheBottomOfTheListOnMount&&(e=0,t=i-1),this.onBeforeShowItems(n,e,t,this.firstSeenItemIndex,this.lastSeenItemIndex),{itemHeights:new Array(i),itemSpacing:void 0,beforeItemsHeight:0,afterItemsHeight:0,firstShownItemIndex:e,lastShownItemIndex:t,scrollY:void 0}}},{key:"getEstimatedItemHeight",value:function(){return this.itemHeights&&this.itemHeights.getAverage()||this.estimatedItemHeight||0}},{key:"getItemSpacing",value:function(){return this.getState()&&this.getState().itemSpacing||0}},{key:"getEstimatedItemsCount",value:function(e){return this.getEstimatedItemHeight()?Math.ceil((e+this.getItemSpacing())/(this.getEstimatedItemHeight()+this.getItemSpacing())):1}},{key:"getEstimatedItemsCountOnScreen",value:function(){return this.scrollableContainer?this.getEstimatedItemsCount(2*this.getMargin()+this.scrollableContainer.getHeight()):1}},{key:"getLastShownItemIndex",value:function(e,t){return this.bypass?t-1:Math.min(e+(this.getEstimatedItemsCountOnScreen()-1),t-1)}},{key:"getItemsCount",value:function(){return this.getState().items.length}},{key:"getMargin",value:function(){return 1*this.scrollableContainer.getHeight()}},{key:"onBeforeShowItems",value:function(e,t,n,i,r){var o=this.onItemFirstRender;if(o)if(void 0===i)for(var s=t;s<=n;)o(e[s]),s++;else{if(t<i)for(var a=t,l=Math.min(n,i-1),u=a;u<=l;)o(e[u]),u++;if(n>r)for(var h=n,d=Math.max(t,r+1);d<=h;)o(e[d]),d++}}},{key:"updateSeenItemIndexes",value:function(){var e=this.firstSeenItemIndex,t=this.lastSeenItemIndex,n=this.getState(),i=n.firstShownItemIndex,r=n.lastShownItemIndex;void 0===e?(e=i,t=r):(i<e&&(e=i),r>t&&(t=r)),this.firstSeenItemIndex=e,this.lastSeenItemIndex=t}},{key:"onMount",value:function(){console.warn("[virtual-scroller] `.onMount()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"render",value:function(){console.warn("[virtual-scroller] `.render()` instance method name is deprecated, use `.listen()` instance method name instead."),this.listen()}},{key:"listen",value:function(){if(!1===this.isRendered)throw new Error("[virtual-scroller] Can't restart a `VirtualScroller` after it has been stopped");A("~ Rendered (initial) ~"),this.isRendered=!0,this.onRendered(),this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.restoreScrollPosition(),this.updateScrollPosition(),this.removeScrollPositionListener=this.scrollableContainer.addScrollListener(this.updateScrollPosition),this.bypass||(this.removeScrollListener=this.scrollableContainer.addScrollListener(this.onScroll),this.scrollableContainerUnlistenResize=this.scrollableContainer.onResize(this.onResize)),this.tbody&&function(e){e.classList.add("VirtualScroller");var t=document.getElementById("VirtualScrollerStyle");t||((t=document.createElement("style")).id="VirtualScrollerStyle",t.innerText="\n\t\t\ttbody.VirtualScroller:before {\n\t\t\t\tcontent: '';\n\t\t\t\tdisplay: table-row;\n\t\t\t\theight: var(--VirtualScroller-paddingTop);\n\t\t\t}\n\t\t\ttbody.VirtualScroller:after {\n\t\t\t\tcontent: '';\n\t\t\t\tdisplay: table-row;\n\t\t\t\theight: var(--VirtualScroller-paddingBottom);\n\t\t\t}\n\t\t".replace(/[\n\t]/g,""),document.head.appendChild(t))}(this.getContainerElement()),this.preserveScrollPositionOfTheBottomOfTheListOnMount?this.scrollTo(0,this.getScrollY()+(this.scrollableContainer.getHeight()-this.preserveScrollPositionOfTheBottomOfTheListOnMount.scrollableContainerContentHeight)):this.onUpdateShownItemIndexes({reason:"mount"})}},{key:"onRendered",value:function(){this.updateItemHeights(),this.tbody&&this.updateTbodyPadding()}},{key:"scrollTo",value:function(e,t){this.scrollableContainer.scrollTo(e,t)}},{key:"getScrollY",value:function(){return this.scrollableContainer.getScrollY()}},{key:"getVisibleAreaBounds",value:function(){var e=this.getScrollY();return{top:e,bottom:e+this.scrollableContainer.getHeight()}}},{key:"getHeight",value:function(){return this.getContainerElement().getBoundingClientRect().height}},{key:"getTopOffset",value:function(){return this.scrollableContainer.getTopOffset(this.getContainerElement())}},{key:"shouldUpdateLayoutOnScrollableContainerResize",value:function(e){if(e&&e.target===window){if(document.fullscreenElement&&this.getContainerElement().contains(document.fullscreenElement))return!1;if(this._shouldUpdateLayoutOnWindowResize&&!this._shouldUpdateLayoutOnWindowResize(e))return!1}var t=this.scrollableContainerWidth,n=this.scrollableContainerHeight;return this.scrollableContainerWidth=this.scrollableContainer.getWidth(),this.scrollableContainerHeight=this.scrollableContainer.getHeight(),this.scrollableContainerWidth===t?this.scrollableContainerHeight!==n&&"UPDATE_INDEXES":"UPDATE_LAYOUT"}},{key:"onUnmount",value:function(){console.warn("[virtual-scroller] `.onUnmount()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"destroy",value:function(){console.warn("[virtual-scroller] `.destroy()` instance method name is deprecated, use `.stop()` instance method name instead."),this.stop()}},{key:"stop",value:function(){this.isRendered=!1,this.removeScrollPositionListener(),this.bypass||(this.removeScrollListener(),this.scrollableContainerUnlistenResize(),g(this.onUserStopsScrollingTimeout),g(this.watchContainerElementCoordinatesTimer))}},{key:"updateTbodyPadding",value:function(){var e=this.getState(),t=e.beforeItemsHeight,n=e.afterItemsHeight;!function(e,t,n){e.style.setProperty("--VirtualScroller-paddingTop",H(t)),e.style.setProperty("--VirtualScroller-paddingBottom",H(n))}(this.getContainerElement(),t,n)}},{key:"updateItemHeights",value:function(){var e=this.getState(),t=e.firstShownItemIndex,n=e.lastShownItemIndex,i=this.getState().firstShownItemIndex;void 0!==t&&(A("~ Measure item heights ~"),this.itemHeights.update(t,n,i),R()&&A("Item heights",this.getState().itemHeights.slice()))}},{key:"updateItemHeight",value:function(e){var t=this.getState().firstShownItemIndex;this.itemHeights.updateItemHeight(e,t)}},{key:"onItemStateChange",value:function(e,t){R()&&(A("~ Item state changed ~"),A("Item",e),A("Previous state\n"+JSON.stringify(this.getState().itemStates[e],null,2)),A("New state\n"+JSON.stringify(t,null,2))),this.getState().itemStates[e]=t}},{key:"onItemHeightChange",value:function(e){var t=this.getState().itemHeights,n=t[e];this.updateItemHeight(e);var i=t[e];n!==i&&(A("~ Item height changed ~"),A("Item",e),A("Previous height",n),A("New height",i),this.onUpdateShownItemIndexes({reason:"item height change"}))}},{key:"getItemCoordinates",value:function(e){for(var t=this.getTopOffset(),n=0;n<e;)t+=this.getState().itemHeights[n],t+=this.getItemSpacing(),n++;return{top:t,bottom:t+this.getState().itemHeights[e],height:this.getState().itemHeights[n]}}},{key:"getVisibleItemIndexes",value:function(e,t,n){for(var i,r,o,s=0,a=!1,l=0;l<this.getItemsCount();){var u=this.itemHeights.get(l);if(void 0===u){A("Item index ".concat(l,' lies within the visible area or its "margins", but its height hasn\'t been measured yet. Mark the item as "shown", render the list, measure the item\'s height and redo the layout.')),o=l,void 0===i&&(i=l);var h=t-(n+s);r=Math.min(l+(this.getEstimatedItemsCount(h)-1),this.getItemsCount()-1),a=!0;break}if(s+=u,void 0===i&&n+s>e&&(A("First visible item index",l),i=l),l<this.getItemsCount()-1&&(s+=this.getItemSpacing()),n+s>t){A("Last visible item index",l),void 0!==i&&(r=l);break}l++}return void 0!==i&&void 0===r&&A("Last item index (is fully visible)",r=this.getItemsCount()-1),this.restoreScrollAfterPrepend&&(r<this.restoreScrollAfterPrepend.index&&(r=this.restoreScrollAfterPrepend.index),a=!1),a&&this.measureItemsBatchSize&&(r=Math.min(r,o+this.measureItemsBatchSize-1)),{firstShownItemIndex:i,lastShownItemIndex:r,redoLayoutAfterRender:a}}},{key:"getOffscreenListShownItemIndexes",value:function(){return{firstShownItemIndex:0,lastShownItemIndex:0,redoLayoutAfterRender:void 0===this.itemHeights.get(0)}}},{key:"getItemIndexes",value:function(e,t,n,i){if(n+i>e&&n<t){var r=this.getVisibleItemIndexes(e,t,n);if(void 0!==r.firstShownItemIndex)return r;A("Off-screen")}else A("Off-screen")}},{key:"getBeforeItemsHeight",value:function(e,t){for(var n=0,i=0;i<e;)n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),n+=this.getItemSpacing(),i++;return n}},{key:"getAfterItemsHeight",value:function(e,t){for(var n=0,i=t+1;i<this.getItemsCount();)n+=this.getItemSpacing(),n+=this.itemHeights.get(i)||this.itemHeights.getAverage(),i++;return n}},{key:"updateWillBeHiddenItemHeightsAndState",value:function(e,t){for(var n=this.getState().firstShownItemIndex;n<=this.getState().lastShownItemIndex;)n>=e&&n<=t||this.updateItemHeight(n),n++}},{key:"watchContainerElementCoordinates",value:function(){var e=this,t=Date.now();!function n(){e.isRendered&&(void 0!==e.topOffset&&e.getTopOffset()!==e.topOffset&&e.onUpdateShownItemIndexes({reason:"top offset change"}),Date.now()-t<3e3&&(e.watchContainerElementCoordinatesTimer=f(n,500)))}()}},{key:"getShownItemIndexes",value:function(){if(this.bypass)return{firstShownItemIndex:0,lastShownItemIndex:this.getItemsCount()-1};var e=this.getTopOffset();void 0===this.topOffset&&this.watchContainerElementCoordinates(),this.topOffset=e;var t=this.getVisibleAreaBounds(),n=t.top,i=t.bottom;return this.latestLayoutVisibleAreaTopAfterIncludingMargin=n-this.getMargin(),this.latestLayoutVisibleAreaBottomAfterIncludingMargin=i+this.getMargin(),this.getItemIndexes(n-this.getMargin(),i+this.getMargin(),e,this.getHeight())||this.getOffscreenListShownItemIndexes()}},{key:"onMultiRenderLayoutRendered",value:function(){var e=this;if(this.redoLayoutAfterRender)return this.redoLayoutAfterRender=void 0,f(function(){e.isRendered&&e.updateShownItemIndexesRecursive()},0);this.stopMultiRenderLayout()}},{key:"stopMultiRenderLayout",value:function(){this.multiRenderLayout=void 0,this.redoLayoutAfterRender||this.restoreScrollAfterPrepend&&this.restoreScroll()}},{key:"captureScroll",value:function(e,t,n){0!==e.length&&(void 0===n&&(n=t.indexOf(e[0])),n<0||0!==n&&(this.getState().firstShownItemIndex>0||this.restoreScrollAfterPrepend&&this.restoreScrollAfterPrepend.previousItems===e&&this.restoreScrollAfterPrepend.nextItems===t||(this.restoreScrollAfterPrepend={previousItems:e,nextItems:t,index:n,visibleAreaTop:this.getItemElement(0).getBoundingClientRect().top})))}},{key:"updateItems",value:function(e,t){return this.setItems(e,t)}},{key:"setItems",value:function(e){var t=arguments.length>1&&void 0!==arguments[1]?arguments[1]:{},n=this.getState().items,i=this.getState(),r=i.firstShownItemIndex,o=i.lastShownItemIndex,s=i.beforeItemsHeight,a=i.afterItemsHeight,l=i.itemStates,u=i.itemHeights,h=(i.itemSpacing,this.firstSeenItemIndex),d=this.lastSeenItemIndex;A("~ Update items ~");var c=D(n,e),m=c.prependedItemsCount,f=c.appendedItemsCount;m>0||f>0?(m>0&&(A("Prepend",m,"items"),u=new Array(m).concat(u),l&&(l=new Array(m).concat(l))),f>0&&(A("Append",f,"items"),u=u.concat(new Array(f)),l&&(l=l.concat(new Array(f)))),r+=m,o+=m,void 0!==h&&(h+=m,d+=m),s+=this.itemHeights.getAverage()*m,a+=this.itemHeights.getAverage()*f):(A("Items have changed, and it's not a simple append and/or prepend: rerender the entire list from scratch."),A("Previous items",n),A("New items",e),h=void 0,d=void 0,u=new Array(e.length),l=new Array(e.length),0===e.length?(r=void 0,o=void 0):(r=0,o=this.getLastShownItemIndex(r,e.length)),s=0,a=0),A("First shown item index",r),A("Last shown item index",o),A("Before items height",s),A("After items height (actual or estimated)",a),this.onBeforeShowItems(e,r,o,h,d),this.preserveScrollPositionOnPrependItems=t.preserveScrollPositionOnPrependItems||t.preserveScrollPosition,this.setState({items:e,itemStates:l,itemHeights:u,firstShownItemIndex:r,lastShownItemIndex:o,beforeItemsHeight:s,afterItemsHeight:a})}},{key:"getItemElement",value:function(e){return this.getContainerElement().childNodes[e]}}])&&B(t.prototype,n),i&&B(t,i),e}()});
 //# sourceMappingURL=virtual-scroller.js.map

package.json

 {
   "name": "virtual-scroller",
-  "version": "1.5.1",
+  "version": "1.5.2",
   "description": "A component for efficiently rendering large lists of variable height items",
@@ -5,0 +5,0 @@ "main": "index.commonjs.js",

README.md

@@ -49,3 +49,3 @@ # VirtualScroller
 
-## Use
+## Core
 
@@ -226,3 +226,3 @@ The default export is the low-level `VirtualScroller` class: it implements the core logic of a `VirtualScroller` component and can be used for building a `VirtualScroller` component for any UI framework. Hence, it's not meant to be used in applications directly: instead, see the high-level components exported from [`virtual-scroller/dom`](#dom) and [`virtual-scroller/react`](#react) packages.
 
-* `setItems(newItems: any[], options: object?)` — Updates `VirtualScroller` `items`. For example, can be used to prepend or append new items to the list. See [Dynamically Loaded Lists](#dynamically-loaded-lists) section for more details. Available options: `preserveScrollPositionOnPrependItems: boolean` — Set to `true` to enable "restore scroll position after prepending items" feature (could be useful when implementing "Show previous items" button).
+* `setItems(newItems: any[], options: object?)` — Updates `VirtualScroller` `items`. For example, it can be used to prepend or append new items to the list. See [Dynamically Loaded Lists](#dynamically-loaded-lists) section for more details. Available options: `preserveScrollPositionOnPrependItems: boolean` — Set to `true` to enable "restore scroll position after prepending new items" feature (should be used when implementing a "Show previous items" button).
 
@@ -409,4 +409,14 @@ * `getItemCoordinates(i: number): object` — Returns coordinates of item with index `i` relative to the document: `top` is the top offset of the item relative to the start of the document, `bottom` is the top offset of the item's bottom edge relative to the start of the document, `height` is the item's height.
 
-The previous examples showcase a static `items` list. For cases when new items are loaded when the user clicks "Show previous" / "Show next" buttons `virtualScroller.setItems(newItems)` method can be used where `newItems` will be `previousItems.concat(items)` for "Show previous" button and `items.concat(nextItems)` for "Show next" button. `virtual-scroller/react` will automatically call `.setItems(newItems)` when new `items` property is passed, and `virtual-scroller/dom` provides a manual `.setItems(newItems)` method same as `VirtualScroller`.
+All previous examples described cases with a static `items` list. When there's a need to update the `items` list, one could use `virtualScroller.setItems(newItems)` instance method. For example, when the user clicks "Show previous items" button, the `newItems` should be set to `previousItems.concat(currentlyShownItems)`, and when the user clicks "Show next items" button, the `newItems` should be set to `currentlyShownItems.concat(nextItems)`.
 
+When using `virtual-scroller/dom` component, a developer should call `.setItems(newItems)` instance method in order to update the items.
+
+When using `virtual-scroller/react` React component, it calls `.setItems(newItems)` method automatically when new `items` property is passed.
+
+The basic equality check (`===`) is used to intelligently compare `newItems` to the existing `items`. If a simple append and/or prepend operation is detected, then the list seamlessly transitions from the current state to the new state, preserving its state and scroll position. If, however, the items have been updated in such a way that it's not a simple append and/or prepend operation, then the entire list is rerendered from scratch, losing its state and resetting the scroll position. There're valid use cases for both situations.
+
+For example, suppose a user navigates to a page where a list of `items: object[]` is shown using a `VirtualScroller`. When a user scrolls down to the last item in the list, a developer might want to query the database for the newly added items, and then show those new items to the user. In that case, the developer could send a query to the API with `afterId: number` parameter being the `id: number` of the last item in the list, and the API would then return a list of the `newItems: object[]` whose `id: number` is greater than the `afterId: number` parameter. Then, the developer would append the `newItems: object[]` to the `items: object[]`, and then call `VirtualScroller.setItems()` with the updated `items: object[]`, resulting in a "seamless" update of the list, preserving its state and scroll position.
+
+Another example. Suppose a user navigates to a page where they can filter a huge list by a query entered in a search bar. In that case, when the user edits the query in the search bar, `VirtualScroller.setItems()` method is called with a list of filtered items, and the entire list is rerendered from scratch. In this case, it's ok to reset the `VirtualScroller` state and the scroll position.
+
 <!--
@@ -416,4 +426,6 @@ `virtualScroller.setItems(newItems)` also receives an optional second `options` argument having shape `{ state }` where `state` can be used for updating "custom state" previously set in `getInitialState(customState)` and can be an `object` or a function `(previousState, { prependedCount, appendedCount }) => object`. If the items update is not incremental (i.e. if `newItems` doesn't contain previous `items`) then both `prependedCount` and `appendedCount` will be `undefined`.
 
-Also, one can use [`on-scroll-to`](https://gitlab.com/catamphetamine/on-scroll-to) library to render a "Load more items on scroll down" component for "infinite scroll" lists.
+When new items are appended to the list, the page scroll position remains unchanged. Same's for prepending new items to the list: the scroll position of the page stays the same, resulting in the list "jumping" down when new items get prepended. To fix that, pass `preserveScrollPositionOnPrependItems: true` option to the `VirtualScroller`. When using `virtual-scroller/dom` component, pass that option when creating a new instance, and when using `virtual-scroller/react` React component, pass `preserveScrollPositionOnPrependItems` property.
 
+For implementing "infinite scroll" lists, a developer could also use [`on-scroll-to`](https://gitlab.com/catamphetamine/on-scroll-to) component.
+
 ## Gotchas
@@ -523,3 +535,3 @@
 
-On March 9th, 2020, GitHub, Inc. silently [banned](https://medium.com/@catamphetamine/how-github-blocked-me-and-all-my-libraries-c32c61f061d3) my account (and all my libraries) without any notice. I opened a support ticked but they didn't answer. Because of that, I had to move all my libraries to [GitLab](https://gitlab.com/catamphetamine).
+On March 9th, 2020, GitHub, Inc. silently [banned](https://medium.com/@catamphetamine/how-github-blocked-me-and-all-my-libraries-c32c61f061d3) my account (erasing all my repos, issues and comments) without any notice or explanation. Because of that, all source codes had to be promptly moved to [GitLab](https://gitlab.com/catamphetamine/virtual-scroller). GitHub repo is now deprecated, and the latest source codes can be found on GitLab, which is also the place to report any issues.
 
@@ -526,0 +538,0 @@ ## License

source/VirtualScroller.js

@@ -259,3 +259,5 @@ // For some weird reason, in Chrome, `setTimeout()` would lag up to a second (or more) behind.
 			firstShownItemIndex,
-			lastShownItemIndex
+			lastShownItemIndex,
+			this.firstSeenItemIndex,
+			this.lastSeenItemIndex
 		)
@@ -328,12 +330,17 @@ return {
 
-	onBeforeShowItems(items, firstShownItemIndex, lastShownItemIndex) {
-		if (this.onItemFirstRender) {
-			if (this.firstSeenItemIndex === undefined) {
+	onBeforeShowItems(
+		items,
+		firstShownItemIndex,
+		lastShownItemIndex,
+		firstSeenItemIndex,
+		lastSeenItemIndex
+	) {
+		const { onItemFirstRender } = this
+		if (onItemFirstRender) {
+			if (firstSeenItemIndex === undefined) {
 				let i = firstShownItemIndex
 				while (i <= lastShownItemIndex) {
-					this.onItemFirstRender(items[i])
+					onItemFirstRender(items[i])
 					i++
 				}
-				this.firstSeenItemIndex = firstShownItemIndex
-				this.lastSeenItemIndex = lastShownItemIndex
 			} else {
@@ -343,22 +350,20 @@ // The library is designed in such a way that
 				// (or touches or contains or is contained by)
-				// `[this.firstSeenItemIndex, this.lastSeenItemIndex]`.
-				if (firstShownItemIndex < this.firstSeenItemIndex) {
+				// `[firstSeenItemIndex, lastSeenItemIndex]`.
+				if (firstShownItemIndex < firstSeenItemIndex) {
 					const fromIndex = firstShownItemIndex
-					const toIndex = Math.min(lastShownItemIndex, this.firstSeenItemIndex - 1)
+					const toIndex = Math.min(lastShownItemIndex, firstSeenItemIndex - 1)
 					let i = fromIndex
 					while (i <= toIndex) {
-						this.onItemFirstRender(items[i])
+						onItemFirstRender(items[i])
 						i++
 					}
-					this.firstSeenItemIndex = firstShownItemIndex
 				}
-				if (lastShownItemIndex > this.lastSeenItemIndex) {
+				if (lastShownItemIndex > lastSeenItemIndex) {
 					const toIndex = lastShownItemIndex
-					const fromIndex = Math.max(firstShownItemIndex, this.lastSeenItemIndex + 1)
+					const fromIndex = Math.max(firstShownItemIndex, lastSeenItemIndex + 1)
 					let i = fromIndex
 					while (i <= toIndex) {
-						this.onItemFirstRender(items[i])
+						onItemFirstRender(items[i])
 						i++
 					}
-					this.lastSeenItemIndex = lastShownItemIndex
 				}
@@ -369,2 +374,24 @@ }
 
+	updateSeenItemIndexes() {
+		let { firstSeenItemIndex, lastSeenItemIndex } = this
+		const { firstShownItemIndex, lastShownItemIndex } = this.getState()
+		if (firstSeenItemIndex === undefined) {
+			firstSeenItemIndex = firstShownItemIndex
+			lastSeenItemIndex = lastShownItemIndex
+		} else {
+			// The library is designed in such a way that
+			// `[firstShownItemIndex, lastShownItemIndex]` always intersects
+			// (or touches or contains or is contained by)
+			// `[firstSeenItemIndex, lastSeenItemIndex]`.
+			if (firstShownItemIndex < firstSeenItemIndex) {
+				firstSeenItemIndex = firstShownItemIndex
+			}
+			if (lastShownItemIndex > lastSeenItemIndex) {
+				lastSeenItemIndex = lastShownItemIndex
+			}
+		}
+		this.firstSeenItemIndex = firstSeenItemIndex
+		this.lastSeenItemIndex = lastSeenItemIndex
+	}
+
 	onMount() {
@@ -646,2 +673,3 @@ console.warn('[virtual-scroller] `.onMount()` instance method name is deprecated, use `.listen()` instance method name instead.')
 			}
+			this.updateSeenItemIndexes()
 			// Stop "multi-render layout" if it's in progress.
@@ -1130,3 +1158,5 @@ if (this.multiRenderLayout) {
 			firstShownItemIndex,
-			lastShownItemIndex
+			lastShownItemIndex,
+			this.firstSeenItemIndex,
+			this.lastSeenItemIndex
 		)
@@ -1352,2 +1382,6 @@ // Render.
 		} = this.getState()
+		let {
+			firstSeenItemIndex,
+			lastSeenItemIndex
+		} = this
 		log('~ Update items ~')
@@ -1361,3 +1395,3 @@ const {
 			if (prependedItemsCount > 0) {
-				log('Prepended items count', prependedItemsCount)
+				log('Prepend', prependedItemsCount, 'items')
 				itemHeights = new Array(prependedItemsCount).concat(itemHeights)
@@ -1369,3 +1403,3 @@ if (itemStates) {
 			if (appendedItemsCount > 0) {
-				log('Appended items count', appendedItemsCount)
+				log('Append', appendedItemsCount, 'items')
 				itemHeights = itemHeights.concat(new Array(appendedItemsCount))
@@ -1378,8 +1412,14 @@ if (itemStates) {
 			lastShownItemIndex += prependedItemsCount
+			if (firstSeenItemIndex !== undefined) {
+				firstSeenItemIndex += prependedItemsCount
+				lastSeenItemIndex += prependedItemsCount
+			}
 			beforeItemsHeight += this.itemHeights.getAverage() * prependedItemsCount
 			afterItemsHeight += this.itemHeights.getAverage() * appendedItemsCount
 		} else {
-			log('Non-incremental items update')
+			log('Items have changed, and it\'s not a simple append and/or prepend: rerender the entire list from scratch.')
 			log('Previous items', previousItems)
 			log('New items', newItems)
+			firstSeenItemIndex = undefined
+			lastSeenItemIndex = undefined
 			itemHeights = new Array(newItems.length)
@@ -1417,3 +1457,5 @@ itemStates = new Array(newItems.length)
 			firstShownItemIndex,
-			lastShownItemIndex
+			lastShownItemIndex,
+			firstSeenItemIndex,
+			lastSeenItemIndex
 		)
@@ -1420,0 +1462,0 @@ // `preserveScrollPosition` property name is deprecated,

No alert changes

Improved metrics

Total package byte prevSize

1542072

increased by1.21%

Lines of code

9378

increased by1.18%

Number of lines in readme file

535

increased by2.29%

No dependency changes