timer na podstawie sekund

function timer(numberOfSeconds){
    var mins = Math.floor(numberOfSeconds / 60);
    var secs = Math.floor(numberOfSeconds % 60);
    if (secs < 10) {
        secs = '0' + String(secs);
    }
    return  mins + ':' + secs;
}

//3:20
console.log(timer(200));