Palindrome Creator

PalindromeCreator.js

function PalindromeCreator(str) {
  const isStringPalindrome = isPalindrome(str);
  if (isStringPalindrome) return 'palindrome';
  const palindrome = findPalindrome([{
    str,
    chars: [],
  }], 2, 0);
  return palindrome && palindrome.str.length > 2 ? getRemovedCharsForPalindrome(palindrome) : 'not possible';
}

function isPalindrome(str) {
  return str === str.split('').reverse().join('');
}

function findPalindrome(combinations, maxCharsToRemove, currentNumCharsRemoved) {
  const allNewCombinations = [];
  for (let i = 0; i < combinations.length; i++) {
    const newCombinations = getCombinationsRemovingOneCharacter(combinations[i]);
    const palindrome = newCombinations.find(combination => isPalindrome(combination.str));
    if (palindrome) return palindrome;
    allNewCombinations.push(...newCombinations);
  }
  if (currentNumCharsRemoved < maxCharsToRemove - 1) {
    const palindrome = findPalindrome(allNewCombinations, maxCharsToRemove, currentNumCharsRemoved + 1);
    if (palindrome) return palindrome;
  }
}

function getCombinationsRemovingOneCharacter(combination) {
  const combinations = [];
  const { str, chars } = combination;
  for (let i = 0; i < str.length; i++) {
    combinations.push({
      str: str.slice(0, i) + str.slice(i + 1),
      chars: [...chars, {
        char: str.slice(i, i + 1),
        index: i,
      }],
    });
  }
  return combinations;
}

function getRemovedCharsForPalindrome(palindrome) {
  return palindrome.chars.sort((a, b) => a.index - b.index).map(char => char.char).join('');
}

console.log(PalindromeCreator('mmop')); // not possible
console.log(PalindromeCreator('kjjjhjjj')); // k
console.log(PalindromeCreator('abjchba')); // jc