Permutations the lazier way (Sorry Heap's Algo)

index.js

function splice(arr, pos) {
  let nArr = Array.from(arr);
  return [ nArr.splice(pos,1), nArr ];
}

function p(arr, result = [], chr = []){
  if (arr.length === 1) result.push(chr.concat(arr).join(''));
  for (let i = 0; i <= arr.length-1; i++) {
    const [c, n] = splice(arr,i);
    p(n,result,chr.concat(c));
  }
  return result;
}

const result = p('abcdefg'.split(''));

console.log(JSON.stringify(result,null,2));
console.log(result.length)