Get the maximum height an element can be to fill the viewport

getMaxHeight.ts

/**
 * Get the maximum height an element can be to fill the viewport.
 *
 * @param el
 * @returns
 */
function getMaxHeight(el: HTMLElement) {
  function pageY(elem: HTMLElement): number {
    return elem.offsetParent
      ? elem.offsetTop + pageY(elem.offsetParent as HTMLElement)
      : elem.offsetTop;
  }

  let height = Math.max(
    document.documentElement.clientHeight || 0,
    window.innerHeight || 0,
  );
  height -= pageY(el);
  height = height < 0 ? 0 : height;

  return height;
}