Anagrams

anagrams.js

/**
 * Return a copy of `array` without element at `index`
 */
const punch = (array = [], index) => {
  const copy = array.slice();
  copy.splice(index, 1);
  return copy;
};

const getAnagrams = (word = '', dedup = true) => {
  const asString = typeof word === 'string';
  const letters = [...word];
  const anagrams = [];

  letters.forEach((letter, i) => {
    const rest = getAnagrams(punch(letters, i));

    if (rest.length) {
      rest.forEach((restLetter) =>
        anagrams.push(
          asString
            ? [letter, ...restLetter].join('')
            : [letter, ...restLetter]
        ));
      return;
    }

    anagrams.push(letter);
  });

  return dedup
    ? Array.from(new Set(anagrams))
    : anagrams;
}

console.log(getAnagrams('xyzz'));
console.log(getAnagrams('xyzz', false));
console.log(getAnagrams(['x', 'y', 'z', 'z']));