jquery活动倒计时

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>jQuery倒计时</title>
    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
</head>
<body>
    <div id="countdown">倒计时: </div>

    <script>
        $(document).ready(function() {
            var endtime = new Date("2023-12-31T23:59:59"); // 设置结束时间
            var interval = setInterval(function() {
                var now = new Date().getTime();
                var distance = endtime - now;
                if (distance < 0) {
                    clearInterval(interval);
                    $('#countdown').html('活动已结束');
                    return;
                }
                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);
                $('#countdown').html('倒计时: ' + days + '天 ' + hours + '小时 ' + minutes + '分钟 ' + seconds + '秒');
            }, 1000);
        });
    </script>
</body>
</html>