Get's element offset from bottom of page to bottom of given element. Useful for test automation to determine if pixel tags are pushing up your footer.

getElemOffsetFromBottom.js

(function(){
  var el = document.querySelector('.footer-wrapper'),
    rect = el.getBoundingClientRect(),
    scrollTopOffset = window.pageYOffset || document.documentElement.scrollTop,
    offsetFromBottom = document.documentElement.scrollHeight - (rect.top + scrollTopOffset + rect.height);
  return offsetFromBottom > 0;
})();