问Hangman游戏不会打印相同的字母

EN

//array of Star Wars Names
var words = ["star wars",
  "senator organa",
  "boba fett",
  "chewbacca",
  "luke skywalker",
  "darth vader",
  "lando calrissian",
  "anakin skywalker",
  "padme amidala"
];

//Declared variables
var rightLetter = [];
var wrongLetter = [];
var underScore = [];
var underScore = [];
var randomWords = Math.floor(Math.random() * words.length);
var chosenWords = words[randomWords];
var starWarsNames = document.getElementsByClassName("Star_Wars_words");
var correctGuess = document.getElementsByClassName("rightGuess");
var incorrectGuess = document.getElementsByClassName("wrongGuess");

//random word array

console.log(chosenWords);

function generateUnderscore() {
  for (i = 0; i < chosenWords.length; i++) {
    underScore.push("_");
  }
  return underScore;
}

//Game Loop
document.addEventListener("keypress", letterPressed);
//letter function
function letterPressed(event) {
  var letter = String.fromCharCode(event.keyCode);
  if (chosenWords.indexOf(letter) > -1) {
    rightLetter.push(letter);
    underScore[chosenWords.indexOf(letter)] = letter;
    starWarsNames[0].innerHTML = underScore.join(" ");
    correctGuess[0].innerHTML = rightLetter;
    if (underScore.join(" ") == chosenWords) {
      alert("The force is strong with you!");
    }
  } else {
    wrongLetter.push(letter);
    incorrectGuess[0].innerHTML = wrongLetter;
  }
}

console.log(rightLetter);
console.log(wrongLetter);
console.log(starWarsNames);

<div class="Star_Wars_words">

</div>
<div class="rightGuess">

</div>
<div class="wrongGuess">

</div>