- From: Ojan Vafai <ojan@chromium.org>
- Date: Mon, 4 Jul 2011 09:28:44 -0700
- To: Boris Zbarsky <bzbarsky@mit.edu>
- Cc: public-webapps@w3.org
- Message-ID: <CANMdWTv2GkUa+o_sPJkEqcNBRrW3umpU0SvMSoOMcF2AmJqVyg@mail.gmail.com>
Apologies in advance if my comment makes no sense. This is a long thread, I tried to digest it all. :) On Sat, Jul 2, 2011 at 7:07 AM, Boris Zbarsky <bzbarsky@mit.edu> wrote: > That may be ok, if the use cases that incur this cost are rare and the > common case can be better served by a different approach. > > Or put another way, if 1% of consumers want the full list because it makes > them 4x faster and the other 99% don't want the full list, and the full list > is 3x slower for the browser to build than just providing the information > the 99% want, what's the right tradeoff? > I'm not sure there really is a performance tradeoff. I believe that the proposal Rafael put forward should almost always be faster. Storing the list of changes and doing a JS callback once, for nearly all use-cases, should be faster than frequent, semi-synchronous callbacks. The only bit that might be slower is what data you include in the mutation list. I believe that all the data you'd need is cheap except for possibly the following two: -The index of the child that changed for ChildListChanged (is this actually expensive?) -The old value of an attribute/text node. I know this is expensive in Gecko's engine at least. I'd be fine with excluding that information by default, but having a flag you pass at some point saying to include those. That way, only sites that need it take the performance hit. > The numbers above are made up, of course; it would be useful to have some > hard data on the actual use cases. > > Maybe we need both sorts of APIs: one which generates a fine-grained change > list and incurs a noticeable DOM mutation performance hit and one which > batches changes more but doesn't slow the browser down as much... > > -Boris > >
Received on Monday, 4 July 2011 16:29:29 UTC