function outerWidth(element) {
  let width = element.offsetWidth;
  const style = getComputedStyle(element);
  width += parseInt(style.marginLeft, 10) + parseInt(style.marginRight, 10);

  return width;
}
Get the current computed width for the given element including margin,
padding and border.
Equivalent to jQuery's `$(el).outerWidth(true)`.
@param {!HTMLElement} element Element.
@return {number} The width.