Hi Andrea,

FWIW, I'd say the best practice is:  Don't do that, it conflates the
model with the view *and* the controller. :-)  (MVC is not by any
means the only game in town, but the terminology is useful for
questions like this.)  If you ever want to present the business object
in two different ways in two different panels (in a list, for
instance, and in a details pane that shows the details of the
highlighted object in the list), you can't, or rather the code gets
ugly fast.

Instead, I'd suggest keeping the business object separate from the
element and using a "has a" rather than an "is a" relationship.  You
can do that by storing the business object ID on the element in some
way ("data-key" is the attribute I usually use for this, and fits with
the proposed HTML5 data attributes standard), either directly or via a
small controller.

The business object should never update the element directly, and so
it doesn't need to know about it.  Instead, it should raise events
that controllers can respond to by updating the elements they
control.  When I say "fire event," I'm not necessarily talking
browserspeak (I wouldn't use browser events for this), just a minimal
implementation of the Observer pattern (as a mixin or similar you can
use for lots of different objects).

FWIW, and apologies if I went OT, but I hope I didn't,
--
T.J. Crowder
tj / crowder software / com
www.crowdersoftware.com


On Sep 9, 3:02 pm, Andrea Campi <andrea.ca...@gmail.com> wrote:
> Hi,
>
> in my application I need JS objects to represent some "business"
> objects, which are represented on the page by an Element.
> I would like to be able to tie the two together in such a way that I
> can use them interchangeably.
> This sounds like it should be a common pattern, so I was wondering
> what the best practices are.
>
> Example:
>
> var Foo = Class.create({
>   initialize: function(parent) {
>     var element = Object.extend(new Element("div", { 'class': 'foo',
> 'id': 'myFoo' }), this);
>     parent.insert(element);
>   },
>
>   bar: function() {
>   }
>   // more methods
>
> };
>
> Thanks to Object.extend I can easily call: $('myFoo').bar()
> But I cannot do the opposite, for instance:
>
> var foo = new Foo();
> foo.childElements();
>
> Note that it would just work if I could return 'element' (which now
> behaves like Foo).
> However, I've readhttp://dev.rubyonrails.org/ticket/11481and it has
> reasonable objections to letting the constructor return a value.
>
> So, what gives? Any suggestion?
>
> TIA,
>   Andrea
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