常见JS倒计时

https://www.jb51.net/Special/356.htm  //JS倒计时 

<button onclick="resetTime(60)">启动倒计时</button>
 <button onclick="countDown(3600)">启动倒计时2</button>

 

//带天数的倒计时
        function countDown(times) {
            var timer = null;
            timer = setInterval(function () {
                var day = 0,
                  hour = 0,
                  minute = 0,
                  second = 0;//时间默认值
                if (times > 0) {
                    day = Math.floor(times / (60 * 60 * 24));
                    hour = Math.floor(times / (60 * 60)) - (day * 24);
                    minute = Math.floor(times / 60) - (day * 24 * 60) - (hour * 60);
                    second = Math.floor(times) - (day * 24 * 60 * 60) - (hour * 60 * 60) - (minute * 60);
                }
                if (day <= 9) day = '0' + day;
                if (hour <= 9) hour = '0' + hour;
                if (minute <= 9) minute = '0' + minute;
                if (second <= 9) second = '0' + second;
                //
                console.log(day + "天:" + hour + "小时：" + minute + "分钟：" + second + "秒");
                times--;
            }, 1000);
            if (times <= 0) {
                clearInterval(timer);
            }
        }
        //单纯分钟和秒倒计时
        function resetTime(time) {
            var timer = null;
            var t = time;
            var m = 0;
            var s = 0;
            m = Math.floor(t / 60 % 60);
            m < 10 && (m = '0' + m);
            s = Math.floor(t % 60);
            function countDown() {
                s--;
                s < 10 && (s = '0' + s);
                if (s.length >= 3) {
                    s = 59;
                    m = "0" + (Number(m) - 1);
                }
                if (m.length >= 3) {
                    m = '00';
                    s = '00';
                    clearInterval(timer);
                }
                console.log(m + "分钟" + s + "秒");
            }
            timer = setInterval(countDown, 1000);
        }