// heights of the document and viewport.
const doc = { height: document.documentElement.offsetHeight };
const viewport = { height: window.innerHeight };
const scrollOffsetY = doc.height - viewport.height;
// scroll to bottom smoothly
document.querySelector('#btn').onclick = () => {
window.scrollTo({
left: 0, top : scrollOffsetY,
behavior: "smooth", // ⭐️ scroll smoothly
});
};
// scroll to top smoothly
document.querySelector('#btn2').onclick = () => {
window.scrollTo({
left: 0, top : 0,
behavior: "smooth", // ⭐️ scroll smoothly
});
};