const { useState, useEffect } = React;

const useOnScreen = (ref) => {
    const [isIntersecting, setIntersecting] = useState(false);
    useEffect(() => {
        const observer = new IntersectionObserver(([entry]) => setIntersecting(entry.isIntersecting));
        if (ref.current) observer.observe(ref.current);
        return () => { if (ref.current) observer.unobserve(ref.current); };
    }, []);
    return isIntersecting;
};

window.useOnScreen = useOnScreen;