W3C home > Mailing lists > Public > public-webapi@w3.org > April 2008

Re: [Element Traversal LC] access to element by index

From: Jonas Sicking <jonas@sicking.cc>
Date: Wed, 02 Apr 2008 02:44:17 -0700
Message-ID: <47F35571.9030209@sicking.cc>
To: Henri Sivonen <hsivonen@iki.fi>
Cc: Boris Zbarsky <bzbarsky@mit.edu>, "Web APIs WG (public)" <public-webapi@w3.org>

Henri Sivonen wrote:
> On Apr 2, 2008, at 00:48, Boris Zbarsky wrote:
>> OK.  So item() would be available on Element after casting it to 
>> NodeList in those implementations.  I guess you're saying that the 
>> cast would not longer be unambiguous if there were multiple NodeLists 
>> that might make sense?  So childElements couldn't be implemented with 
>> a |return this;|?
>> That doesn't seem like such a terrible implementation burden to me, to 
>> be honest...
> I'm not claiming it would be awfully hard, but it does change the impact 
> of Element Traversal from adding four or five methods on an existing 
> class (mere code footprint; super-simple) to adding more run-time object 
> instances. And then, there are issues like should childElements return 
> the same object every time. And if yes, then the implementor needs to 
> add a new pointer to each element node or to add a hashtable on the 
> owner document or something along those lines. Again, not awfully hard, 
> but still more complex than just adding convenience methods on an 
> existing class.

Sure it's more complex, but it's still trivial.

> And to what end? To use indexing instead of list-style 
> iteration.

Exactly. Something that I would imagine is quite commonly done. Note 
that we're not just talking iterating over a full DOM tree, we're also 
talking about navigating around in a DOM tree from one known specific 
node to another.

/ Jonas
Received on Wednesday, 2 April 2008 09:45:23 UTC

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