Given a sorted string, either return a shortened version of it where the character is accompanied by an integer representing how many times it's in the string. If the shortened version is longer than the original, return the original

shortenedString.js

const shortened = str => {
  let newStr = "",
      charCount = 1;
      
  for (let i = 0; i < str.length; i++) {
    if (charCount < 2 && str[i] != str[i + 1]) {
      newStr += str[i];
      charCount = 1;
    } else if (str[i] != str[i + 1]) {
      newStr += str[i] + charCount;
      charCount = 1;
    } else {
      charCount++;
    }
  }
  
  return newStr.length > str.length ? str : newStr;
}

shortened("aaabbbbccccc")