Countdown timer

countdown.js

//<editor-fold desc="Таймер обратного отсчета">
var t_data = document.getElementById('tender_data'); // get element with data-set
var timer_end_date = t_data.getAttribute('data-timer-end'); // get data-set timer-end
var timerHour = $('.b-timer_wrap > .i-hour'); // where to write hours value
var timerMin = $('.b-timer_wrap > .i-minute'); // where to write minutes value
var timerSec = $('.b-timer_wrap > .i-sec'); // where to write seconds value
    
function zero(number) {
        return (number < 10 ? '0' : '') + number;
    }

var timer = setInterval(function(){updateWCTime()}, 100 );

function updateWCTime() {
    now      = new Date();
    kickoff  = Date.parse(timer_end_date);
    diff = kickoff - now;

    if (diff > 0) {
        days  = Math.floor( diff / (1000*60*60*24) );
        hours = Math.floor( diff / (1000*60*60) );
        mins  = Math.floor( diff / (1000*60) );
        secs  = Math.floor( diff / 1000 );

        dd = days;
//        hh = hours - days  * 24;
        hh = hours;
        mm = mins  - hours * 60;
        ss = secs  - mins  * 60;

        timerHour.text(zero(hh));
        timerMin.text(zero(mm));
        timerSec.text(zero(ss));
    } else { // What to do if countdown reached it's limit (in my case I'll write 00 for HH:MM:SS)
        timerHour.text('00');
        timerMin.text('00');
        timerSec.text('00');
        clrInt(timer);
        return false;
    }

}

function clrInt(int) {
    clearInterval(int); // прекратить функцию setInterval
}
//</editor-fold>