JS时钟问题，开始onclick

<div id="clock">
  <span id="hours">00</span> :
  <span id="minutes">00</span> :
  <span id="seconds">00</span>
</div>

#clock {
  font-family: Arial, sans-serif;
  font-size: 24px;
  color: #333;
}

// 获取容器和子元素的引用
var clockContainer = document.getElementById('clock');
var hoursElement = document.getElementById('hours');
var minutesElement = document.getElementById('minutes');
var secondsElement = document.getElementById('seconds');

// 更新时钟的显示
function updateClock() {
  var now = new Date();
  var hours = now.getHours();
  var minutes = now.getMinutes();
  var seconds = now.getSeconds();

  // 格式化时间，确保显示为两位数
  hours = hours < 10 ? '0' + hours : hours;
  minutes = minutes < 10 ? '0' + minutes : minutes;
  seconds = seconds < 10 ? '0' + seconds : seconds;

  // 更新时钟的显示
  hoursElement.textContent = hours;
  minutesElement.textContent = minutes;
  secondsElement.textContent = seconds;
}

// 每秒更新一次时钟
setInterval(updateClock, 1000);

var startButton = document.getElementById('startButton');
startButton.onclick = function() {
  setInterval(updateClock, 1000);
};