Get Scroll Amount; returns {left:NUM, top:NUM}

get_scroll_amount.js

(()=>{
  function getScrollAmount(){
    const doc = document.documentElement;

    return {
      left: (window.pageXOffset || doc.scrollLeft) - (doc.clientLeft || 0),
      top: (window.pageYOffset || doc.scrollTop)  - (doc.clientTop || 0)
    };
  }

  return getScrollAmount();
})();