30-seconds-of-code/snippets/bottom-visible.md

Bottom visible

Returns true if bottom of the page is visible. It adds scrollY to the height of the visible portion of the page (clientHeight) and compares it to pageHeight to see if bottom of the page is visible.

const bottomVisible = () => {
  const scrollY = window.scrollY;
  const visibleHeight = document.documentElement.clientHeight;
  const pageHeight = document.documentElement.scrollHeight;
  const bottomOfPage = visibleHeight + scrollY >= pageHeight;

  return bottomOfPage || pageHeight < visibleHeight;
}