array sorting javascript mergesort

// Merge Sort (Recursive)
function mergeSort (unsortedArray) {
  // No need to sort the array if the array only has one element or empty
  if (unsortedArray.length <= 1) {
    return unsortedArray;
  }
  // In order to divide the array in half, we need to figure out the middle
  const middle = Math.floor(unsortedArray.length / 2);

  // This is where we will be dividing the array into left and right
  const left = unsortedArray.slice(0, middle);
  const right = unsortedArray.slice(middle);

  // Using recursion to combine the left and right
  return merge(
    mergeSort(left), mergeSort(right)
  );
}