export function scrollHandler() { const body = document.body; const scrollUp = 'scroll-up'; const scrollDown = 'scroll-down'; let lastScroll = 0; window.addEventListener('scroll', () => { const currentScroll = window.pageYOffset; if (currentScroll <= 0) { body.classList.remove(scrollUp); return; } if (currentScroll > lastScroll && !body.classList.contains(scrollDown)) { body.classList.remove(scrollUp); body.classList.add(scrollDown); } else if (currentScroll < lastScroll && body.classList.contains(scrollDown)) { body.classList.remove(scrollDown); body.classList.add(scrollUp); } lastScroll = currentScroll; }); }