如何将随机数字链接到字母表中的字母，无重复项

function getRandomLetter() {
  var alphabet = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'];
  
  var randomIndex = Math.floor(Math.random() * alphabet.length);
  var randomLetter = alphabet[randomIndex];
  
  return randomLetter;
}

function generateRandomLink() {
  var previousLetter = '';
  var randomLink = '';
  
  for (var i = 0; i < alphabet.length; i++) {
    var randomLetter = getRandomLetter();
    
    while (randomLetter === previousLetter) {
      randomLetter = getRandomLetter();
    }
    
    randomLink += randomLetter;
    previousLetter = randomLetter;
  }
  
  return randomLink;
}

var randomLink = generateRandomLink();
console.log(randomLink);