Javascript :停止使用clearInterval时setInterval计时器无法再次重新启动

let timer = null;

function startTimer() {
  if (timer === null) {
    timer = setInterval(function() {
      // 定时器逻辑
    }, 1000);
  }
}

function stopTimer() {
  if (timer !== null) {
    clearInterval(timer);
    timer = null;
  }
}

let isTimerRunning = false;

function timerLogic() {
  // 定时器逻辑
}

function startTimer() {
  if (!isTimerRunning) {
    setInterval(timerLogic, 1000);
    isTimerRunning = true;
  }
}

function stopTimer() {
  if (isTimerRunning) {
    clearInterval(timer);
    isTimerRunning = false;
  }
}