var Observer = new Class({

	options: {
		periodical: false,
		delay: 1000
	},

	initialize: function(el, onFired, options){
		this.setOptions(options);
		this.addEvent('onFired', onFired);
		this.element = $(el);
		this.listener = this.fired.bind(this);
		this.value = this.element.getValue();
		if (this.options.periodical) this.timer = this.listener.periodical(this.options.periodical);
		else this.element.addEvent('keyup', this.listener);
	},

	fired: function() {
		var value = this.element.getValue();
		if (this.value == value) return;
		this.clear();
		this.value = value;
		this.timeout = this.fireEvent.delay(this.options.delay, this, ['onFired', [value]]);
	},

	clear: function() {
		$clear(this.timeout);
		return this;
	}
});

Observer.implement(new Options);
Observer.implement(new Events);