function pagination(c, m) {
        var current = c,
            last = m,
            delta = 2,
            left = current - delta,
            right = current + delta + 1,
            range = [],
            rangeWithDots = [],
            l;

        for (let i = 1; i <= last; i++) {
            if (i == 1 || i == last || i >= left && i < right) {
                range.push(i);
            }
        }

        for (let i of range) {
            if (l) {
                if (i - l === 2) {
                    rangeWithDots.push(l + 1);
                } else if (i - l !== 1) {
                    rangeWithDots.push('...');
                }
            }
            rangeWithDots.push(i);
            l = i;
        }
        return rangeWithDots;
    }

I'm finding the other implement to learning,...

String.prototype.toHHMMSS = function () {
        var sec_num = parseInt(this, 10);
        var hours = Math.floor(sec_num / 3600);
        var minutes = Math.floor((sec_num - (hours * 3600)) / 60);
        var seconds = sec_num - (hours * 3600) - (minutes * 60);

        if (hours < 10) {
            hours = "0" + hours;
        }
        if (minutes < 10) {
            minutes = "0" + minutes;
        }
        if (seconds < 10) {
            seconds = "0" + seconds;
        }
        return hours + ":" + minutes + ":" + seconds;
    };

    let storeTimeOutKey = "timeOut"

    let time = new Date();
    let minutely = 60 * 1000

    var cachedTimeOut = localStorage.getItem(storeTimeOutKey)
    if(cachedTimeOut){
        time = JSON.parse(cachedTimeOut)
    }
    else{
        time.setTime(time.getTime() + minutely * 6)
        localStorage.removeItem(storeTimeOutKey)
        localStorage.setItem(storeTimeOutKey, JSON.stringify(time.getTime()))
    }

    // var timer = setInterval(Countdown(time / 1000), 1000)

    function Countdown(startTime) {
        return () => {
            let curTime = (new Date()).getTime() / 1000;
            let result = (`${startTime - curTime}`).toHHMMSS();
            console.log(result)

            let isTimeOut = parseInt(startTime - curTime, 10) == 0
            if(isTimeOut){
                clearInterval(timer)
                return;
            }
        }
    }