Flip 2D array vertically or horizontally.

gistfile1.txt

let array = [
  [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9]
]

const flip = (array, direction = 'HORIZONTAL') => {
  const temp = [...array]
  if (direction.toUpperCase() === 'VERTICAL') {
    return (temp.reverse())
  } else {
    return (temp.map(arr => arr.reverse()))
  }
}

console.log('HOR', flip(array, 'HORIZONTAL')) // "HOR", [[3, 2, 1], [6, 5, 4], [9, 8, 7]]
console.log('VERT', flip(array, 'VERTICAL')) // "VERT", [[9, 8, 7], [6, 5, 4], [3, 2, 1]]