How to implement a web page countdown function in php

In modern society, countdown is a situation we often encounter in our daily lives. Whether it's the start time of a countdown event or the deadline of an important event, we always need a corresponding countdown function to remind us to keep track of the latest progress. Countdown can be used in multiple scenarios: such as the start time of a major promotion posted on the website, such as the limited time discount time of a certain product, etc. So, how to use PHP to implement a web page countdown?

1. Time formatting

In PHP, we usually use timestamp to represent the current time and target time. The timestamp refers to the total number of seconds from 0:00:00 on January 1, 1970 to the current time (or target time). We can get the timestamp of the current time through PHP's time() function.

$current_timestamp = time();

Next, we need to format the timestamp of the target time into a more readable date and time string. You can use PHP's date() function to convert a timestamp into a string in a specified format.

$target_timestamp = strtotime('2022-01-01 00:00:00');
$target_time = date('Y-m-d H:i:s', $target_timestamp);

In the above example, we used the strtotime() function to convert the target time in string format into a timestamp, and then used the date() function to convert the timestamp into a date-time string in the specified format. . This target time can be any time we need to countdown, such as the start time of an event, the limited-time discount time of a certain product, etc.

2. Countdown calculation

Next, we need to calculate the time difference from the current time to the target time to determine the remaining time of the countdown.

$diff_timestamp = $target_timestamp - $current_timestamp;
$days = floor($diff_timestamp / (24*60*60));
$hours = floor(($diff_timestamp % (24*60*60)) / (60*60));
$minutes = floor(($diff_timestamp % (60*60)) / 60);
$seconds = $diff_timestamp % 60;

In the above example, we use arithmetic operators and the floor() function to calculate the number of days, hours, minutes and seconds remaining to the target time. Among them, $days represents the remaining days, $hours represents the remaining hours, $minutes represents the remaining minutes, and $seconds represents the remaining seconds.

3. Countdown display

After we have the remaining time, we can display the corresponding countdown on the web page.

<div id="countdown"></div>

<script>
    function countdown(){
        var days = <?php echo $days; ?>;
        var hours = <?php echo $hours; ?>;
        var minutes = <?php echo $minutes; ?>;
        var seconds = <?php echo $seconds; ?>;

        document.getElementById("countdown").innerHTML = 
            "倒计时 " + days + " 天 " + hours + " 小时 " + minutes + " 分钟 " + seconds + " 秒 ";

        if(seconds > 0) {
            seconds--;
        } else {
            seconds = 59;
            if(minutes > 0) {
                minutes--;
            } else {
                minutes = 59;
                if(hours > 0) {
                    hours--;
                } else {
                    hours = 23;
                    if(days > 0) {
                        days--;
                    } else {
                        clearInterval(intervalId);
                        document.getElementById("countdown").innerHTML = "倒计时结束";
                    }
                }
            }
        }
    }

    var intervalId = setInterval(countdown, 1000);
</script>

In the above example, we created a