Timer 타이머

JS

// timer
function countdown( elementId, seconds ){
    var element, endTime, hours, mins, msLeft, time;

    function updateTimer(){
        msLeft = endTime - (+new Date);
        if ( msLeft < 0 ) {
            console.log('done');
        } else {
            time = new Date( msLeft );
            // hours = time.getUTCHours();
            // mins = time.getUTCMinutes();
            hours = String(time.getUTCHours()).padStart(2, "0");
            mins = String(time.getUTCMinutes()).padStart(2, "0");

            element.innerHTML = (hours ? ('0' + mins).slice(-2) : mins) + ':' + ('0' + time.getUTCSeconds()).slice(-2);
            setTimeout( updateTimer, time.getUTCMilliseconds());
        }
    }

    element = document.getElementById( elementId );
    endTime = (+new Date) + 1000 * seconds;
    updateTimer();
}

countdown('countdown', 181);	 // 180 = 3분 1초