export function normalizeWheel (event) {
  let delta = {x: 0, y: 0}
  if (event.wheelDelta) { // WebKit / Opera / Explorer 9
    delta = event.wheelDelta
  } else if (event.detail) { // Firefox older
    delta = -event.detail
  }else if (event.deltaY) { // Firefox
    delta = -event.deltaY
  }

  return delta
}
