bytes = length => {
  if (length < 1e3) {
    return `${length / 1e3}KB`;
  }
  if (length < 1e6) {
    return `${Math.round(length / 100) / 10}KB`;
  }
  return `${Math.round(length / (1000 * 100)) / 10}MB`;
}
Beautify a file size
@param {number} length