Кнопка,таймер

function Timer(sec, el) {
  this.sec = sec || 1000;
  this.cb;
  this.el = el || (function() {
    var timerEl = document.createElement('div');
    document.body.appendChild(timerEl);
    return timerEl;
  }());
}
 
Timer.prototype.timer = function() {
  var that = this;
  this.countdown = new Date();
  this.responseTime = new Date(Date.now() + 1000 * this.sec);
  return function recurFn() {
    that.countdown.setTime(that.responseTime - Date.now());
    if (that.countdown.getTime() > 0) {
            that.render();
      requestAnimationFrame(recurFn);
    } else {
      that.stop();
    }
  };
};
 
Timer.prototype.start = function(callback) {
  var timerFn = this.timer()
  this.timerID = requestAnimationFrame(timerFn);
  this.cb = callback;
};
 
Timer.prototype.stop = function() {
  cancelAnimationFrame(this.timerID);
  this.cb.call(this);
};
Timer.prototype.render = function() {
      this.el.innerHTML = this.countdown.getUTCHours() + ':' + this.countdown.getUTCMinutes() + ':' + this.countdown.getUTCSeconds();
};
var timer1 = new Timer(5);
var timer2 = new Timer(20);
var timer3 = new Timer(10);
 
timer1.start(function() {
 
  alert('Первый стоп!')
});
timer2.start(function() {
 
  alert('Второй стоп!')
});
timer3.start(function() {
 
  alert('Третий стоп!')
});

timer1.start(function() {
 
  alert('Первый стоп!')
});

timer1.start(function() {
 
  alert('Первый стоп!')
});
timer2.start(function() {
 
  alert('Второй стоп!')
});
timer3.start(function() {
 
  alert('Третий стоп!')
});