class Abstract.TimedObserver
Description
An abstract DOM element observer class, subclasses of which can be used to periodically check a value and trigger a callback when the value has changed.
A TimedObserver
object will try to check a value using the getValue()
instance method which must be defined by the subclass. There are two out-of-the-box subclasses:
Form.Observer
, which serializes a form and triggers when the result has changed; and
Form.Element.Observer
, which triggers when the value of a given form field changes.
Creating Your Own TimedObserver Implementations
It's easy to create your own TimedObserver
implementations: Simply subclass TimedObserver
and provide the getValue()
method. For example, this is the complete source code for
Form.Element.Observer
:
Form.Element.Observer = Class.create(Abstract.TimedObserver, {
getValue: function() {
return Form.Element.getValue(this.element);
}
});