docs: function getNativeScrollbarWidth() {
      let outer = document.createElement('div');
      outer.style.overflowY = 'scroll';
      outer.setAttribute('class', _(this).scrollbarClass);
      outer.style.visibility = 'hidden';
      outer.style.width = '100px';
      document.body.appendChild(outer);
      let content = document.createElement('div');
      outer.appendChild(content);
      var width = 100 - Math.floor(content.getBoundingClientRect().width);
      document.body.removeChild(outer);
      return width;
  }