code: function getScrollParent(element) {
    // Return body, `getScroll` will take care to get the correct `scrollTop` from it
    if (!element) {
      return document.body;
    }
  
    switch (element.nodeName) {
      case 'HTML':
      case 'BODY':
        return element.ownerDocument.body;
      case '#document':
        return element.body;
    }
  
    // Firefox want us to check `-x` and `-y` variations as well
    const { overflow, overflowX, overflowY } = getStyleComputedProperty(element);
    if (/(auto|scroll|overlay)/.test(overflow + overflowY + overflowX)) {
      return element;
    }
  
    return getScrollParent(getParentNode(element));
  }
docs: Returns the scrolling parent of the given element
  @method
  @memberof Popper.Utils
  @argument {Element} element
  @returns {Element} scroll parent