我需要安排一个计时器

Question

我正在尝试建立一个递增计时器，即使您更改或刷新页面，它也必须计算出解决票证的时间，当该页面结束时，用户必须单击停止按钮，但是我有一个问题，当它计数时，我按下按钮Stop and reset可以正常工作，但是当我刷新网站时，它仍在计数并且没有停止。

这是我的网站：

var countDownDate = localStorage.getItem('startDate');
if (countDownDate) {
  countDownDate = new Date(countDownDate);
} else {
  countDownDate = new Date();
  localStorage.setItem('startDate', countDownDate);
}
var x = setInterval(function() {
  var now = new Date().getTime();
  var distance = now - countDownDate.getTime();
  var days = Math.floor(distance / (1000 * 60 * 60 * 24));
  var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((distance % (1000 * 60)) / 1000);
  document.getElementById("demo").innerHTML = days + "d " + hours + "h " + minutes + "m " + seconds + "s ";
}, 1000);

function Reset() {
  var countDownDate = localStorage.getItem('startDate');
  if (countDownDate == 0, clearInterval(x)) {
    countDownDate = new Date(countDownDate);
  } else {
    countDownDate = new Date();
    localStorage.setItem('startDate', countDownDate);
  }
}

<button onclick="Reset()">Stop and Reset</button>
<p id="demo"></p>