image-element-bounding.js

const isInViewport = ({ top, height, windowHeight }) => {
  const scroll = window.scrollY || window.pageYOffset;
  const boundsTop = top + scroll;

  const viewport = {
    top: scroll,
    bottom: scroll + windowHeight,
  };

  const bounds = {
    top: boundsTop,
    bottom: boundsTop + height,
  };

  return (bounds.bottom >= viewport.top && bounds.bottom <= viewport.bottom)
    || (bounds.top <= viewport.bottom && bounds.top >= viewport.top);
};