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import { useRef, useCallback } from 'react';
export function useSnapScroll() {
const autoScrollRef = useRef(true);
const scrollNodeRef = useRef<HTMLDivElement>();
const onScrollRef = useRef<() => void>();
const observerRef = useRef<ResizeObserver>();
const messageRef = useCallback((node: HTMLDivElement | null) => {
if (node) {
const observer = new ResizeObserver(() => {
if (autoScrollRef.current && scrollNodeRef.current) {
const { scrollHeight, clientHeight } = scrollNodeRef.current;
const scrollTarget = scrollHeight - clientHeight;
scrollNodeRef.current.scrollTo({
top: scrollTarget,
});
}
});
observer.observe(node);
} else {
observerRef.current?.disconnect();
observerRef.current = undefined;
}
}, []);
const scrollRef = useCallback((node: HTMLDivElement | null) => {
if (node) {
onScrollRef.current = () => {
const { scrollTop, scrollHeight, clientHeight } = node;
const scrollTarget = scrollHeight - clientHeight;
autoScrollRef.current = Math.abs(scrollTop - scrollTarget) <= 10;
};
node.addEventListener('scroll', onScrollRef.current);
scrollNodeRef.current = node;
} else {
if (onScrollRef.current) {
scrollNodeRef.current?.removeEventListener('scroll', onScrollRef.current);
}
scrollNodeRef.current = undefined;
onScrollRef.current = undefined;
}
}, []);
return [messageRef, scrollRef];
}
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