form_observer.js

$.fn.observe = function(time, callback) {
	return this.each(function() {
		var form = $(this)
		var serialized = form.serialize();

		setInterval(function() {
			if (serialized != form.serialize()) {
				serialized = form.serialize();
				callback.call(form);
			}
		}, time * 1000);
	});
};