    <!DOCTYPE html>
    <html>
    <head>
      <meta charset="UTF-8">
      <title>주기적으로 실행하기</title>
      <link rel="stylesheet" href="style_js.css">
    </head>
    <body style="text-align: center">
      <h2>현재 시각</h2><hr>
      <h1 id="clock">00:00:00</h1>
      <script>
        function updateClock() {
          const now = new Date();
          const hours = now.getHours().toString().padStart(2, '0');
          const minutes = now.getMinutes().toString().padStart(2, '0');
          const seconds = now.getSeconds().toString().padStart(2, '0');
          const timeString = `${hours}:${minutes}:${seconds}`;
          const clockElement = document.getElementById('clock');
          clockElement.textContent = timeString;
        }
        setInterval(updateClock, 1000);
      </script>
    </body>
    </html>