Rotate.js

<script>
var array = [];
arrayX = 4;
arrayY = 4;
var rotate = ({oa}) =>
{
  var na = [];
  for (let i = 0; i < arrayX; i++)
  {
    na[i] = [];
    for (let j = 0; j < arrayY; j++)
    {
      na[i][j] = oa[4 - j - 1][i];
    }
  }
  return na;
}
var log = () =>
{
  for (let i = 0; i < arrayX; i++)
  {
    console.log(array[i]);
  }
}

for (let i = 0; i < arrayX; i++)
{
  array[i] = [];
  for (let j = 0; j < arrayY; j++)
  {
    array[i][j] = `${i}` + ` ${j}`;
  }
}

console.log("Old Array:")
log();
array = rotate({oa : array});
console.log("New Rotated Array:")
log();

</script>

Little experiment to rotate an array using javascript.
I know it's n^2 but frankly I don't mind given the use case