heaps algorithm in javascript for all permutations O(n!)

heaps-algo.js

const swap = (a, b, arr) => {
  const temp = arr[a];
  arr[a] = arr[b];
  arr[b] = temp;
};

// heaps algorithm
const getCombinations = (inputArr) => {
  const heaps = (result, arr, n) => {
    n ??= arr.length;
    if (n === 1) {
      return result.push([...arr]);
    }

    for (let i = 0; i < n - 1; i++) {
      heaps(result, arr, n - 1);
      swap(n % 2 ? 0 : i, n - 1, arr);
    }
    heaps(result, arr, n - 1);
  };
  const result = [];
  heaps(result, inputArr);
  return result;
};