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import { useState, useEffect, useCallback, RefObject } from 'react';
export const useInfiniteScroll = ({
ref,
hasMore,
onLoadMore,
}: {
onLoadMore: Function;
hasMore: boolean;
ref: RefObject<HTMLElement>;
}): [boolean, () => void] => {
const [isFetching, setIsFetching] = useState(false);
const handleScroll = useCallback(() => {
if (ref.current!.scrollTop === 0 && isFetching === false && hasMore) {
// starts to fetch if scrolled to top, fetching is not in progress and has more data
setIsFetching(true);
}
}, [ref, isFetching, hasMore]);
useEffect(() => {
const elem = ref.current;
if (!elem) {
return;
}
elem.addEventListener('scroll', handleScroll);
return () => {
elem!.removeEventListener('scroll', handleScroll);
};
}, [ref, handleScroll]);
// loads more if fetching has started
useEffect(() => {
if (isFetching) {
onLoadMore();
}
}, [isFetching, onLoadMore]);
const stopFetching = useCallback(() => {
setIsFetching(false);
}, []);
return [isFetching, stopFetching];
};
export default useInfiniteScroll;
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