📜 Automatically scroll a page

Here’s a cool little script I created that automatically scrolls down/up a page smoothly.

Useful for showcasing parallax elements within an iframe.

function frame() {
  const el = document.documentElement;
  el.scrollTop += el.dataset.autoScrollDir === "down" ? 1 : -1;
  const hitBottom = el.scrollTop + el.clientHeight >= el.scrollHeight;
  if (hitBottom) document.documentElement.dataset.autoScrollDir = "up";
  const hitTop = el.scrollTop <= 0;
  if (hitTop) document.documentElement.dataset.autoScrollDir = "down";
  requestAnimationFrame(frame);
}
document.documentElement.dataset.autoScrollDir = "down";
requestAnimationFrame(frame);