倒计时（PHP和js）

php

function daojishi(){
        /*活动倒计时*/
        $today =time();   //当前时间戳 6月7号
        $end_time = '2020-12-12 23:59:59';  //一般由数据库查询出来的活动结束时间
        $second = strtotime($end_time)-$today; //结束时间戳减去当前时间戳
        if($second <= 0){
            echo 'hhhhh';die;
        }
        // echo $second;
        $day = floor($second/3600/24);    //倒计时还有多少天
        $hr = floor($second/3600%24);     //倒计时还有多少小时（%取余数）
        $min = floor($second/60%60);      //倒计时还有多少分钟
        $sec = floor($second%60);         //倒计时还有多少秒
        $str = $day."天".$hr."小时".$min."分钟".$sec."秒";  //组合成字符串
        echo $str;
    }

js

<script>
    countDown();
    function addZero(i) {
        return i < 10 ? "0" + i: i + "";
    }
    function countDown() {
        var enddate = $('#enddate').val();
        var nowtime = new Date();
        var endtime = new Date(enddate);
        var lefttime = parseInt((endtime.getTime() - nowtime.getTime()) / 1000);
        var d = parseInt(lefttime / (24*60*60))
        var h = parseInt(lefttime / (60 * 60) % 24);
        var m = parseInt(lefttime / 60 % 60);
        var s = parseInt(lefttime % 60);
        d = addZero(d)
        h = addZero(h);
        m = addZero(m);
        s = addZero(s);
        document.querySelector(".djsd").innerHTML = d;
        document.querySelector(".djsh").innerHTML = h;
        document.querySelector(".djsm").innerHTML = m;
        document.querySelector(".djss").innerHTML = s;
        if (lefttime <= 0) {
            document.querySelector(".djsd").innerHTML = 0;
            document.querySelector(".djsh").innerHTML = 0;
            document.querySelector(".djsm").innerHTML = 0;
            document.querySelector(".djss").innerHTML = 0;
            return;
        }
        setTimeout(countDown, 1000);
    }
</script>