Generate all possible words with a given set of characters

allPossibleCombinations.js

function allPossibleCombinations(input, fixedLength, currentCombination) {
  if (currentCombination.length == fixedLength) {
    return [currentCombination];
  }
  
  const combinations = [];
  
  for (let i = 0; i < input.length; i++) {
    combinations.push(...allPossibleCombinations(input, fixedLength, currentCombination + input[i]));
  }

  return combinations;
}

const input = ['a', '1'];
console.log(allPossibleCombinations(input, 2, '')); // ['aa', 'a1', '1a', '11']