dataCasting.js

const itemsToTable = items => {
  return items.reduce((prevItem, currentItem) => {
    const cursor = prevItem.length > 0 ? prevItem.length - 1 : 0
    
    if (!Array.isArray(prevItem[cursor])) {
      prevItem[cursor] = []
    }

    const currentColumn = cursor >= 0 ? prevItem[cursor] : []
    
    const isEmptyColumn = currentColumn.length === 0
    const isWinningHand = currentColumn[0].WinningHand === currentItem.WinningHand

    if (isEmptyColumn || isWinningHand) {
      prevItem[cursor].push(currentItem)
    }

    if (!isEmptyColumn && !isWinningHand) {
      prevItem[cursor + 1] = [currentItem]
    }

    return prevItem
  }, [])
}