html页面基于ajax按钮60秒倒计时

可以通过以下步骤实现：

1. 在 HTML 页面中添加一个按钮和一个显示倒计时的元素：

<button id="countdown-btn">开始倒计时</button>
<span id="countdown">60</span>

2. 在 JavaScript 中定义一个计时器，并在按钮点击时启动计时器：

var countdown = 60;
var countdownInterval;

document.getElementById("countdown-btn").addEventListener("click", function() {
  countdownInterval = setInterval(function() {
    countdown--;
    document.getElementById("countdown").innerText = countdown;
    if (countdown <= 0) {
      clearInterval(countdownInterval);
    }
  }, 1000);
});

3. 当计时器倒计时结束时，清除计时器并重置倒计时：

clearInterval(countdownInterval);
countdown = 60;
document.getElementById("countdown").innerText = countdown;

完整的代码如下所示：

<button id="countdown-btn">开始倒计时</button>
<span id="countdown">60</span>

<script>
var countdown = 60;
var countdownInterval;

document.getElementById("countdown-btn").addEventListener("click", function() {
  countdownInterval = setInterval(function() {
    countdown--;
    document.getElementById("countdown").innerText = countdown;
    if (countdown <= 0) {
      clearInterval(countdownInterval);
    }
  }, 1000);
});
</script>