My Solution Of Rotate-Matrix question

Once i was asked to write a code which, given a matrix "rotates" it in a way that the "rows" become "columns".
For example:

const matrix = [
  [1,2,3],
  [4,5,6],
  [7,8,9]
]

Should become:

const result = [
  [1,4,7],
  [2,5,8],
  [3,6,9]
]

here is y solution for this challenge

function r(mat) {
  return mat.reduce((acc, row, idx) => {
     return [...acc, mat.map(itm => itm[idx])]
  }, [])
}
let res = r(matrix)
console.log({res})

Or it can be written as one row:

const r = mat => mat.reduce((acc, row, idx) => [...acc, mat.map(itm => itm[idx])], [])
let res = r(matrix)
console.log({res})