Implement timer function using PHP

In the past, I only knew that JS could be used to implement the timer function, and it was very convenient. However, during the project today, I needed to implement a functional module. When I was doing a certain part of it, I thought it would be great if I could implement the timer function through PHP. So I searched online and found that similar functions can be achieved by using the ignore_user_abort() function together with the set_time_limit() function and an infinite loop. Although the project did not use this function in the end, I felt that the potential use value was still very high, so I later referred to some information on the Internet and compiled it as follows:

<?php
    // 1、范例代码：
    ignore_user_abort(true);  // 设置与客户机断开是否会终止脚本的执行。
    set_time_limit(0);        // 设置脚本超时时间，为0时不受时间限制
    ob_end_clean();           // 清空缓存
    ob_start();               // 开始缓冲数据
    while(1){
        echo str_repeat(" ",1024);  // 写满IE有默认的1k buffer
        ob_flush();                 // 将缓存中的数据压入队列
        flush();                    // 输出缓存队列中的数据
        echo "now time is ".date('h:i:s');  // 打印数据，其实是先将数据存入了缓存中
        usleep(1000000);            //延迟一秒（暂停一秒）
    }
    // 该段程序实现的功能是每隔一秒钟输出一次包含当前时间的字符串。

    // 2、说明：
    // 经过测试，范例结果中会出现不连续输出，如果要求实现连续、均匀的输出效果（如输出时间），则应设置缓存；为方便理解，提供相关函数作用说明如下：
    /*
    ①ignore_user_abort(bool):设置与客户机断开是否会终止脚本的执行。
    ②set_time_limit(int seconds)设置允许脚本运行的时间，单位为秒。参数值为0时不受限制。
    ③ob_end_clean()：清除服务端缓存的数据
    ④ob_start()：开启一个缓存（可嵌套）
    ⑤ob_flush()：将缓存中的数据压入队列
    ⑥flush()：输出缓存队列中的数据
    ⑦usleep(int m-seconds)：以指定的微秒数延缓程序的执行。
    */
    // 注：
    // flush()和ob_flush()的正确顺序应是，先ob_flush()再flush()，不可弄混。
    // usleep()函数可替换成sleep()函数，不同之处在于sleep()的参数是秒。

The above has introduced the use of PHP to implement the timer function, including various aspects. I hope it will be helpful to friends who are interested in PHP tutorials.