代码示例:(标识:jsck_win_setinterval_3)
<!DOCTYPE html>
<html>
<body>

<h1>Window 对象</h1>

<h2>setInterval() 方法</h2>

<p id="demo"></p>

<script>
setInterval(myTimer, 1000);

function myTimer() {
  const date = new Date();
  document.getElementById("demo").innerHTML = date.toLocaleTimeString();
}
</script>

</body>
</html>
运行结果: