On Fri, 12 Feb 2010 12:51:03 +0100, Maciej Stachowiak <[email protected]>
wrote:
On Feb 12, 2010, at 3:47 AM, Maciej Stachowiak wrote:
On Feb 12, 2010, at 3:19 AM, Anne van Kesteren wrote:
On Fri, 22 Jan 2010 14:11:40 +0100, Anton Muhin <[email protected]>
wrote:
Is it possible to allow caching for those cases? Firefox caches those
node lists for a long time (Maciej found the related bug
https://bugzilla.mozilla.org/show_bug.cgi?id=140758). IE8 caches as
well. Opera, Safari and Chrome do not.
Sorry for the somewhat late reply. We'd prefer not to change the
specification here and keep the requirement. We're afraid of potential
hard to detect incompatibility bugs if you sometimes cache and
sometimes don't. We're also not convinced that you cannot get the
performance win by other means.
Since Firefox and IE both cache, how would it create compatibility bugs
for other browsers to do so as well? I think we should remove the
requirement unless Firefox and IE are willing to change their
implementations.
I would hope they fix their bugs in due course, yes. Specifically leaving
the behavior undefined seems like a bad idea. We know that from other
areas.
In addition, I should mention that likely the only observable difference
is in setting custom ("expando") properties. If you make two equivalent
requests for a NodeList, setting a property on one will show up on the
other only in the case where there was caching. However, I think use of
expando properties on NodeLists is unlikely. Sacrificing a lot of
performance for a marginal hypothetical improvement in predictability of
behavior does not seem like a good tradeoff.
Is it really a lot of performance? Our developers are not that convinced.
Also it has been suggested to me that just-in-time optimizations might not
work well if different users start polluting the same object (if nodelists
are shared).
--
Anne van Kesteren
http://annevankesteren.nl/
