// Nav function Nav() { const [scrolled, setScrolled] = React.useState(false); React.useEffect(() => { const onScroll = () => setScrolled(window.scrollY > 8); window.addEventListener('scroll', onScroll, { passive: true }); onScroll(); return () => window.removeEventListener('scroll', onScroll); }, []); return ( ); } Object.assign(window, { Nav });