Given two strings, write a method to decide if one is a permutation of the other.

isperm.js

function perm(str) {
  return _perm(str, "").toString().split(',');
}

function _perm(str, acc) {
  if (str.length === 0) return acc;
  else {
    return str.split('').map((c, i) => {
      let s = str.substr(0, i) + str.substr(i+1);
      return _perm(s, acc + str[i]);
    });
  }
}

function isPerm(str, test) {
  // over-complicated
  // return perm(str).includes(test);
  // simple...
  return str.split('').sort().join('') == test.split('').sort().join('');
}

console.log(isPerm("lewis", "siwel"));