显示javascript中的时钟/时间增量

var currentTime = new Date();

function updateClock() {
  var currentTime = new Date();
  var hours = currentTime.getHours();
  var minutes = currentTime.getMinutes();
  var seconds = currentTime.getSeconds();

  // 添加前导零
  hours = (hours < 10 ? "0" : "") + hours;
  minutes = (minutes < 10 ? "0" : "") + minutes;
  seconds = (seconds < 10 ? "0" : "") + seconds;

  // 显示时钟
  var clockElement = document.getElementById("clock");
  clockElement.innerHTML = hours + ":" + minutes + ":" + seconds;
}

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

function getTimeIncrement() {
  var currentTime = new Date();
  var specifiedTime = new Date("2022-01-01 00:00:00");

  // 计算时间差值（单位为毫秒）
  var timeDifference = specifiedTime.getTime() - currentTime.getTime();

  // 将时间差值转换为小时、分钟和秒
  var hours = Math.floor(timeDifference / (1000 * 60 * 60));
  var minutes = Math.floor((timeDifference % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((timeDifference % (1000 * 60)) / 1000);

  // 显示时间增量
  var incrementElement = document.getElementById("increment");
  incrementElement.innerHTML = hours + "小时 " + minutes + "分钟 " + seconds + "秒";
}

// 每秒钟更新一次时间增量
setInterval(getTimeIncrement, 1000);

<p id="clock"></p>
<p id="increment"></p>