commit 701829400e78b32f8ad1a132ca3b915e4be4aebd · kitten.sh/use-interactions

src/index.ts

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       export * from './useDialogFocus';

     

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       export * from './useMenuFocus';

     

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       export * from './useDismissable';

     

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       export * from './useScrollRestoration';

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src/useScrollRestoration.ts

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       import { useLayoutEffect } from './utils/react';

     

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       import { Ref } from './types';

     

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       const mutationObservers: Map<HTMLElement, MutationObserver> = new Map();

     

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       const resizeListeners: Map<HTMLElement, Array<() => void>> = new Map();

     

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       const resizeObserver = new ResizeObserver(entries => {

     

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         const parents = new Set<Element>();

     

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         for (let i = 0; i < entries.length; i++) {

     

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           const parent = entries[i].target.parentElement;

     

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           if (parent && !parents.has(parent)) {

     

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             parents.add(parent);

     

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             const listeners = resizeListeners.get(parent) || [];

     

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             for (let i = 0; i < listeners.length; i++) listeners[i]();

     

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           }

     

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         }

     

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       });

     

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       function observeScrollHeight(

     

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         element: HTMLElement,

     

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         onScrollHeightChange: (scrollHeight: number) => void

     

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       ): () => void {

     

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         const listeners = resizeListeners.get(element) || [];

     

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         const isFirstListener = !listeners.length;

     

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         resizeListeners.set(element, listeners);

     

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         let previousScrollHeight: null | number = null;

     

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         let hasUnmounted = false;

     

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         const onResize = () => {

     

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           const scrollHeight = element.scrollHeight || 0;

     

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           if (!hasUnmounted && scrollHeight !== previousScrollHeight) {

     

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             onScrollHeightChange(element.scrollHeight);

     

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             previousScrollHeight = scrollHeight;

     

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           }

     

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         };

     

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         listeners.push(onResize);

     

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         if (isFirstListener) {

     

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           const mutationObserver = new MutationObserver(entries => {

     

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             for (let i = 0; i < entries.length; i++) {

     

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               const entry = entries[i];

     

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               for (let j = 0; j < entry.addedNodes.length; j++) {

     

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                 const node = entry.addedNodes[j];

     

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                 if (node.nodeType === Node.ELEMENT_NODE) {

     

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                   resizeObserver.observe(node as Element);

     

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                 }

     

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               }

     

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               for (let j = 0; j < entry.removedNodes.length; j++) {

     

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                 const node = entry.removedNodes[j];

     

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                 if (node.nodeType === Node.ELEMENT_NODE) {

     

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                   resizeObserver.unobserve(node as Element);

     

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                 }

     

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               }

     

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             }

     

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           });

     

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           const childNodes = element.childNodes;

     

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           for (let i = 0; i < childNodes.length; i++)

     

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             if (childNodes[i].nodeType === Node.ELEMENT_NODE)

     

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               resizeObserver.observe(childNodes[i] as Element);

     

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           mutationObserver.observe(element, { childList: true });

     

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           mutationObservers.set(element, mutationObserver);

     

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         }

     

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         requestAnimationFrame(onResize);

     

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         return () => {

     

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           const listeners = resizeListeners.get(element) || [];

     

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           listeners.splice(listeners.indexOf(onResize), 1);

     

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           hasUnmounted = true;

     

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           if (!listeners.length) {

     

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             const mutationObserver = mutationObservers.get(element);

     

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             if (mutationObserver) mutationObserver.disconnect();

     

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             const childNodes = element.childNodes;

     

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             for (let i = 0; i < childNodes.length; i++)

     

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               if (childNodes[i].nodeType === Node.ELEMENT_NODE)

     

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                 resizeObserver.unobserve(childNodes[i] as Element);

     

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             resizeListeners.delete(element);

     

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             mutationObservers.delete(element);

     

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           }

     

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         };

     

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       }

     

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       const getIdForState = (() => {

     

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         const defaultState = {};

     

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         const stateToId = new WeakMap<{}, string>();

     

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         let uniqueID = 1;

     

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         return (state?: {} | null): string => {

     

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           if (!state) state = defaultState;

     

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           let id = stateToId.get(state);

     

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           if (!id) stateToId.set(state, (id = (uniqueID++).toString(36)));

     

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           return `${id}${document.location}`;

     

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         };

     

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       })();

     

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       const scrollPositions: Record<string, number> = {};

     

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       export function useScrollRestoration<T extends HTMLElement>(

     

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         ref: 'window' | Ref<T>

     

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       ) {

     

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         useLayoutEffect(() => {

     

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           let unsubscribe: void | (() => void);

     

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           if (ref !== 'window' && !ref.current) return;

     

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           const addonId = ref === 'window' ? 'window' : ref.current!.id || '';

     

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           const eventTarget = ref === 'window' ? window : ref.current!;

     

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           const scrollTarget = ref === 'window' ? document.body : ref.current!;

     

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           function restoreScroll(event?: PopStateEvent) {

     

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             const id = `${addonId}${getIdForState(

     

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               event ? event.state : history.state

     

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             )}:${window.location}`;

     

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             const scrollHeight =

     

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               ref === 'window'

     

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                 ? document.body.scrollHeight

     

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                 : ref.current!.scrollHeight;

     

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             const scrollY = scrollPositions[id];

     

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             if (!scrollY) {

     

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               // noop

     

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             } else if (scrollHeight >= scrollY) {

     

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               scrollTarget.scrollTo(0, scrollY);

     

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             } else {

     

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               if (unsubscribe) unsubscribe();

     

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               unsubscribe = observeScrollHeight(

     

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                 ref === 'window' ? document.body : ref.current!,

     

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                 (scrollHeight: number) => {

     

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                   // the scroll position shouldn't have changed by more than half the screen height

     

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                   const hasMoved =

     

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                     Math.abs(scrollY - scrollPositions[id]) > window.innerHeight / 2;

     

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                   // then we restore the position as it's now possible

     

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                   if (!hasMoved && scrollHeight >= scrollY)

     

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                     scrollTarget.scrollTo(0, scrollY);

     

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                   if (unsubscribe) unsubscribe();

     

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                 }

     

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               );

     

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             }

     

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           }

     

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           function onScroll() {

     

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             const id = `${addonId}${getIdForState(history.state)}:${window.location}`;

     

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             const scrollY =

     

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               ref === 'window' ? window.scrollY : ref.current!.scrollTop;

     

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             scrollPositions[id] = scrollY || 0;

     

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             if (unsubscribe) {

     

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               unsubscribe();

     

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               unsubscribe = undefined;

     

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             }

     

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           }

     

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           restoreScroll();

     

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           const eventOpts = { passive: true } as EventListenerOptions;

     

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           eventTarget.addEventListener('scroll', onScroll, eventOpts);

     

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           window.addEventListener('popstate', restoreScroll);

     

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           return () => {

     

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             eventTarget.removeEventListener('scroll', onScroll, eventOpts);

     

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             window.removeEventListener('popstate', restoreScroll);

     

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             if (unsubscribe) unsubscribe();

     

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           };

     

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         }, [ref]);

     

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       }