function permutations(str, permutation = '') {
  if (!str || str.length === 0) {
    console.log(permutation);
    return;
  }

  let newPermutation, newStr;
  for (let i = 0; i < str.length; i++) {
    newPermutation = permutation + str.slice(i, i+1);
    newStr = str.substr(0, i) + str.substr(i + 1, str.length);

    permutations(newStr, newPermutation)
  }
}