count the word that have at least 1 same letter from other word in the sentence

countSameLetterInWord.js

// count the word that have at least 1 same letter from other word in the sentence,
// will check letters only special characters will be ignored
function countSameLetterInWord(sentence) {

  // remove special characters from the input 
  let input = sentence.replace(/[^a-zA-Z ]/g, ""); 
  //console.log(input);
  let words = input.split(" ");
  let tempWords;
  let tempLetter;
  let found;
  let i = 0;
  let result = [];

  words.forEach((word) => {

    tempWords = words.filter(val => val !== word);
    //console.log(tempWords);

    tempWords.forEach((tempWord) => {
      i = word.length;
      //console.log(i+" "+tempWord);

      while (i > 0) {
         i--;
         tempLetter = word.charAt(i);
         //console.log(tempLetter);
         found = isLetterInWord(tempLetter, tempWord);
         //console.log(found);
         if (found) {
          result.push(tempWord);
         }
      }
    });
  });
  
  return countUnique(result);
}

let input = "apple banana?? c??cc nnnnY zzzzz! !yyyy"; // 4
console.log("result: "+ countSameLetterInWord(input));

function isLetterInWord(letter, word) {
  return word.includes(letter);
}

function countUnique(iterable) {
  return new Set(iterable).size;
}