maestro-server/client-app

export default function getScrollBarWidth () {
  if (document.documentElement.scrollHeight <= document.documentElement.clientHeight) {
    return 0
  }
  const inner = document.createElement('p')
  inner.style.width = '100%'
  inner.style.height = '200px'

  const outer = document.createElement('div')
  outer.style.position = 'absolute'
  outer.style.top = '0px'
  outer.style.left = '0px'
  outer.style.visibility = 'hidden'
  outer.style.width = '200px'
  outer.style.height = '150px'
  outer.style.overflow = 'hidden'
  outer.appendChild(inner)

  document.body.appendChild(outer)
  const w1 = inner.offsetWidth
  outer.style.overflow = 'scroll'
  let w2 = inner.offsetWidth
  if (w1 === w2) w2 = outer.clientWidth

  document.body.removeChild(outer)

  return (w1 - w2)
}