rijkvanzanten

function getViewPercentage(element) {
  const viewport = {
    top: window.pageYOffset,
    bottom: window.pageYOffset + window.innerHeight
  };

  const elementBoundingRect = element.getBoundingClientRect();
  const elementPos = {
    top: elementBoundingRect.y + window.pageYOffset,
    bottom: elementBoundingRect.y + elementBoundingRect.height + window.pageYOffset