text: //Reverse Vowels of a String
  //Given a string s, reverse only all the vowels in the string and return it.
  //The vowels are 'a', 'e', 'i', 'o', and 'u', and they can appear in both cases.
  
  function reverseVowels(s){
    if(s.length === 0){
      return s;
    }
    let vowels = 'aeiouAEIOU';
    let characters = s.split('');
    let left = 0;
    let right = s.length - 1;
    let temp;
    
    while(left < right){
      while(left < right && vowels.indexOf(characters[left]) === -1){
        left++;
      }
      while(left < right && vowels.indexOf(characters[right]) === -1){
        right--;
      }
  
      temp = characters[right];
      characters[right] = characters[left];
      characters[left] = temp;
      left++;
      right--;
    }
    return characters.join('');
  }
  
  // console.log(reverseVowels('hello'));