How to get changed value in Form.Observer

Dmitry Polushkin
2007-10-31T11:05:50Z

Hi everybody!

First of all, prototype is a great library.

But I have a problem with getting the last changed value in
Form.Observer. Have already asked that question in Prototype: Core
mailing list, but nobody asked me yet. So sorry for duplicating it
here also.

For example, if I''ll do:

new Form.Observer($(form), 0.2, some_callback_function);

function some_callback_function() {
  console.log(this.getValue());
  console.log(this.lastValue());

}

It will log two different strings. But how to get diff between those
two values?

I need that, because I have much of elements in form, and I need to
get name of the element, that have just changed. Form.Element.Observer
isn''t suit to solve my problem, because I have set of radio buttons
(first argument of Form.Element.Observer is ID of input element).

In previous example, I can search for string, like:

---

Radio buttons name: hinge_id, form: step3

Helper:

function $RC(form, name) {
        return $(form).getInputs(''radio'',
name).find(function(radio) {
                if (radio.checked) {
                        return radio;
                }
        });

}

In callback:

var hinge_id = $RC(''step3'', ''hinge_id'');
if (hinge_id != null) {
        var hinge_id_regexp = new RegExp(''hinge_id=([0-9]+)'');
        hinge_id_before = this.lastValue.match(hinge_id_regexp);
        hinge_id_now = this.getValue().match(hinge_id_regexp);

        if (hinge_id_before != null && hinge_id_before[1]
!hinge_id_now[1])
{
                console.log(hinge_id_before + '':'' +
hinge_id_now);
        }

}

---

but is it a good practice, or?

Thank you for your help,
Dmitry


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