Rotate 2D Array

rotate2dArray.js

export default const rotate2dArray = array => {
  const resultLength = array[0].length
  const resultArray = Array(resultLength).fill([])
  return resultArray.map((x, widthIndex) =>
    array.map(innerArray => innerArray[widthIndex])
  )
}

rotate2dArray.spec.js

import rotate2dArray from './rotate2dArray'

describe('rotate2dArray', () => {
  it('should rotate array 90 degrees', () => {
    const input = [[1, 2, 3], [4, 5, 6]]
    const expected = [[1, 4], [2, 5], [3, 6]]
    expect(rotate2dArray(input)).toEqual(expected)
  })
})