//From prototype.js                
    var PeriodicalExecuter = new Class({
        // name: 'PeriodicalExecuter',
        initialize: function(callback, frequency) {
        
            this.callback = callback;
            this.frequency = frequency;
            this.currentlyExecuting = false;

            this.registerCallback();
        },

        registerCallback: function() {
        
            this.stop();
            this.timer = setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
            return this;
        },

        execute: function() {
        
            this.callback(this);
            return this;
        },

        stop: function() {
        
            if (!this.timer) return this;
            clearInterval(this.timer);
            this.timer = null;
            return this;
        },

        onTimerEvent: function() {
        
            if (!this.currentlyExecuting) {
            
                try {
                
                    this.currentlyExecuting = true;
                    this.execute();
                } finally {
                
                    this.currentlyExecuting = false;
                }
                
                return this;
            }
        }
    });

    /*
        countdown class
    */var CountDown = new Class({options: {
    
            date: null,
            onChange: $empty,
            onComplete: $empty
        },
        initialize: function (options) {
    
            this.setOptions(options);
            
            this.timer = new PeriodicalExecuter(this.update.bind(this), 1);
        },
        update: function () {
        
            var stop = false;
            var time = Math.floor((this.options.date.getTime() - new Date().getTime()) / 1000);
            
            var countdown = {days: Math.floor(time / (60 * 60 * 24)), 'time': time};
            
            if(time <= 0) time = 0;
            
            if(time == 0) stop = true;
            
            time %= (60 * 60 * 24);
            
            countdown.hours = Math.floor(time / (60 * 60));
            time %= (60 * 60);
            countdown.minutes = Math.floor(time / 60);
            countdown.second = time % 60;
            
            this.fireEvent('onChange', countdown);
            
            if(stop) {
            
                this.timer.stop();
                this.fireEvent('onComplete');
            }
        },
        Implements: [Options, Events]
    });