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useObserver.ts
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38 lines (31 loc) · 944 Bytes
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import { useEffect, useRef, useState } from "react";
const useIntersectionObserver = (callback: () => void) => {
const [observeTarget, setObserveTarget] = useState<HTMLElement | null>(null);
const observer = useRef<IntersectionObserver | null>(null);
const savedCallback = useRef(callback);
useEffect(() => {
savedCallback.current = callback;
}, [callback]);
useEffect(() => {
if (!observer.current) {
observer.current = new IntersectionObserver(
([entry]) => {
if (entry.isIntersecting) {
savedCallback.current();
}
},
{ threshold: 1 }
);
}
if (observeTarget) {
observer.current.observe(observeTarget);
}
return () => {
if (observer.current && observeTarget) {
observer.current.unobserve(observeTarget);
}
};
}, [observeTarget]);
return setObserveTarget;
};
export default useIntersectionObserver;