Snail

snail-rotate.js

const flipMatrix = matrix => (
  matrix[0].map((column, index) => (
    matrix.map(row => row[index])
  ))
);

const rotateMatrix = matrix => (
  flipMatrix(matrix.reverse())
);

/*
Sure enough, this function rotates the matrix clockwise:

[                             [
  [1,2,3],                      [7,4,1],
  [4,5,6],         ->           [8,5,2],
  [7,8,9],                      [9,6,3],
];                             ];
*/