优化JavaScript测验游戏：实现问题全部答完即结束的逻辑

// timer function/Count down
function startTimer() {
  let timeInterval = setInterval(
    () => {
      timeLeft--;
      document.getElementById("timeSpan").innerHTML = timeLeft;
      if (timeLeft <= 0) {
        clearInterval(timeInterval);
        gameOver();
      }
    }, 1000
  );
};

function nextquestion(event) {
  if (event.target.className === "btn") {
    // ... 处理答案和分数逻辑 ...
    currentQuestion++; // 递增当前问题索引
    displayQuestion(); // 尝试显示下一个问题
  }
};

// calling in id/class from HTML 
const questionEl = document.getElementById("question");
const checkers = document.getElementById("right-wrong"); // 未使用，可移除
// const timerEl = document.getElementsByClassName("timeSpan"); // 此处获取的是HTMLCollection，直接用ID更好
const answerOne = document.getElementById("answer1");
const answerTwo = document.getElementById("answer2");
const answerThree = document.getElementById("answer3");
const answerFour = document.getElementById("answer4");
const finalScoreEl = document.getElementById("pointScore");
const nameEl = document.getElementById("initials"); // 未使用，可移除
const highScoreEl = document.getElementById("highScoreList"); // 未使用，可移除

// 测验问题数据
var questionKey = [
  {
    question: "which variable has the value of a string.",
    choiceOne: "x = 6",
    choiceTwo: "x = \"87\"",
    choiceThree: "x = true",
    choiceFour: "x;",
    answer: "x = \"87\""
  },
  {
    question: "choose the operator that checks for value and type.",
    choiceOne: "=",
    choiceTwo: "+=",
    choiceThree: "===",
    choiceFour: "<=;",
    answer: "==="
  },
  {
    question: "choose the true statement.",
    choiceOne: "4 != 4",
    choiceTwo: "4 > 85",
    choiceThree: "7 === \"7\"",
    choiceFour: "7.6 == \"7.6\"",
    answer: "7.6 == \"7.6\""
  },
  {
    question: "which data type is not primitive.",
    choiceOne: "boolean",
    choiceTwo: "array",
    choiceThree: "number",
    choiceFour: "string",
    answer: "array"
  },
  {
    question: "Which one is the Increment operator.",
    choiceOne: "**",
    choiceTwo: "/",
    choiceThree: "++",
    choiceFour: "+=",
    answer: "++"
  }
];

// 游戏状态变量
let timeLeft = 60;
let score = 0;
let currentQuestion = -1;
let finalScore;
let timeInterval; // 声明为全局变量，以便在任何地方清除

// 切换页面显示区域
function changeDiv(curr, next) {
  document.getElementById(curr).classList.add('hide');
  document.getElementById(next).removeAttribute('class');
};

// 启动游戏
document.querySelector('#startButton').addEventListener('click', gameStart);

function gameStart() {
  changeDiv('start', 'questionHolder');
  currentQuestion = 0;
  displayQuestion();
  startTimer();
};

// 计时器函数
function startTimer() {
  timeInterval = setInterval(
    () => {
      timeLeft--;
      document.getElementById("timeSpan").innerHTML = timeLeft;
      if (timeLeft <= 0) {
        clearInterval(timeInterval);
        gameOver();
      }
    }, 1000
  );
};

// 显示当前问题
function displayQuestion() {
  questionEl.textContent = questionKey[currentQuestion].question;
  answerOne.textContent = questionKey[currentQuestion].choiceOne;
  answerTwo.textContent = questionKey[currentQuestion].choiceTwo;
  answerThree.textContent = questionKey[currentQuestion].choiceThree;
  answerFour.textContent = questionKey[currentQuestion].choiceFour;
}

// 处理用户点击答案
document.querySelector('#questionHolder').addEventListener('click', nextquestion);

function nextquestion(event) {
  if (event.target.className === "btn") {
    // 检查答案是否正确
    if (event.target.textContent === questionKey[currentQuestion].answer) {
      score += 10;
      console.log("correct");
    } else {
      // 答案错误，扣除时间
      if (timeLeft >= 10) {
        timeLeft -= 10;
        document.getElementById("timeSpan").innerHTML = timeLeft;
        console.log("not correct");
      } else {
        timeLeft = 0; // 时间不足10秒，直接归零并结束游戏
        clearInterval(timeInterval); // 确保结束时清除计时器
        gameOver();
        return; // 提前返回，避免后续逻辑执行
      }
    }

    // 递增当前问题索引
    currentQuestion++;

    // 检查是否所有问题都已回答完毕
    if (currentQuestion === questionKey.length) {
      clearInterval(timeInterval); // 清除计时器
      gameOver(); // 结束游戏
    } else {
      displayQuestion(); // 如果还有问题，则显示下一个问题
    }
  }
};

// 游戏结束函数
function gameOver() {
  // 确保计时器显示为0，因为可能在时间未归零时结束游戏
  document.getElementById("timeSpan").innerHTML = 0; 
  changeDiv('questionHolder', 'finishedPage');
  finalScore = score;
  finalScoreEl.textContent = finalScore;
};