JAVASCRIPT

use useRef to get current class

const Navbar = () => {
    const navbar = useRef(null)
    window.addEventListener('scroll', () => {
        if (window.scrollY > navbar.current.offsetHeight + 550) {
            navbar.current.classList.add('active');
        }else{
            navbar.current.classList.remove('active');
        }
    });
    return (
        <Fragment>
            <nav id='navbar' className="nav" ref={navbar}>
                <div className="container">
                    <h1 className="logo"><a href="/index.html"></a>My Website</h1>
                    <ul>
                        <li><a href="#" className="current">Home</a></li>
                        <li><a href="#">About</a></li>
                        <li><a href="#">Services</a></li>
                        <li><a href="#">Contact</a></li>
                     </ul>
                </div>
            </nav>
            {/* other elements */}
        </Fragment>
    )
}