chunkArray = (arr, chunkCount) => {
  if (chunkCount === 1) return [arr]
  const chunked = []
  let position = 0
  for (let i = 0; i < chunkCount; i++) {
    const chunkLength = Math.ceil((arr.length - position) / (chunkCount - i))
    chunked.push([])
    chunked[i] = arr.slice(position, chunkLength + position)
    position += chunkLength
  }
  return chunked
}
Chunk array into sub-arrays
@param {Array} arr
@param {Number} chunkCount
@returns {Array<Array>}