Hallar las permutaciones de un string.

stringPermutations.js

const stringPermutations = str => {
  if (str.length === 1) return [str];
  return str
    .split('')
    .reduce(
      (acc, letter, i) => 
        acc.concat(
          stringPermutations(str.slice(0, i) + str.slice(i + 1)
        )
        .map(val => letter + val))
      ,[]
    );
};

console.log('Result', stringPermutations('abcde'))