时间倒计时提醒

        var countDown = function (minute, callback) {
            var allSecond = minute * 60;
            var tickTimer = null;

            var start = function() {
                tickTimer = setInterval(()=>{
                    -- allSecond;
                    if (allSecond == -1) {
                        stop();
                        callback && callback('finish');
                    } else {
                        extract(allSecond);
                    };
                }, 1000);
            };

            var extract = function(second) {
                var m = Math.floor(second / 60),
                    s = second % 60;
                if (m > 0) {
                    callback && callback('value', `${m} 分 ${s} 秒`);
                } else {
                    callback && callback('value', `${s} 秒`);
                };
            };

            var stop = function() {
                clearInterval(tickTimer);
            };

            return {
                start: start,
                stop: stop
            };
        };

        var diffTime = function() {

            var endTime,
                waitMinute;    // 当前时间和设定时间的差值(分钟)

            endTime = getSameDay().concat(...arguments);
            return getMinByMil();

            function getSameDay() {
                var time = new Date();
                var year = time.getFullYear(),
                    mon = time.getMonth(),
                    day = time.getDate();
                return [year, mon, day];
            };

            function getMinByMil(mil) {
                var endTimeMs = new Date(...endTime).getTime();
                waitMinute = Math.ceil((endTimeMs - new Date().getTime()) / 1000 / 60);
                return waitMinute;
            };
        };

        // 比如当前时间为15: 58你设置为16:00:01做某件事,则可以这样
        var time = diffTime(16, 00, 1);
        countDown(time, function(state, v) {
            if (state === 'finish') {
                console.log('时间到');
            } else if (state === 'value') {
                console.log(v);
            };
        }).start();