import { useCallback, useEffect, useState } from 'react'; interface UseScrollToTopOptions< T > { scrollTargetRef: React.MutableRefObject< T | null >; smoothScrolling: boolean; isBelowThreshold: ( scrollTarget: T ) => boolean; } type ScrollTarget = HTMLElement | Window; export const useScrollToTop = < T extends ScrollTarget >( { scrollTargetRef, smoothScrolling, isBelowThreshold, }: UseScrollToTopOptions< T > ) => { const [ isButtonVisible, setVisible ] = useState( false ); const scrollCallback = useCallback( () => { if ( scrollTargetRef.current ) { setVisible( isBelowThreshold( scrollTargetRef.current ) ); } }, [ scrollTargetRef, isBelowThreshold ] ); useEffect( () => { if ( scrollTargetRef.current ) { const scrollElement = scrollTargetRef.current; scrollElement.addEventListener( 'scroll', scrollCallback ); return () => { scrollElement.removeEventListener( 'scroll', scrollCallback ); }; } }, [ scrollTargetRef, scrollCallback ] ); const scrollToTop = useCallback( () => { if ( ! scrollTargetRef.current ) { return; } scrollTargetRef.current.scrollTo( { top: 0, behavior: smoothScrolling ? 'smooth' : 'auto', } ); }, [ scrollTargetRef, smoothScrolling ] ); return { scrollToTop, isButtonVisible, }; };