- From: Boris Zbarsky <bzbarsky@MIT.EDU>
- Date: Mon, 18 Nov 2013 15:23:53 -0500
- To: Jonas Sicking <jonas@sicking.cc>
- CC: "Tab Atkins Jr." <jackalmage@gmail.com>, Domenic Denicola <domenic@domenicdenicola.com>, "public-script-coord@w3.org" <public-script-coord@w3.org>
On 11/18/13 3:11 PM, Jonas Sicking wrote: > One thing that very well might be worth optimizing is when a function > is passed a "plain" Array as the iterable. Right, that's the only case really worth optimizing. > We'd of course have to detect that no custom iterator "fragile and non-trivial". ;) > or custom numeric getters We don't check for that now, we just blindly get using the slow path that would handle them, fwiw. In practice nothing is gated on the performance of this bit that I've seen. > I would expect that this is an optimization that the JS engine is > interested in doing internally too, for things like Array.concat etc. It is and they do. It's a pretty subtle optimization, though, and easy to get wrong. Even easier to become wrong later. -Boris
Received on Monday, 18 November 2013 20:24:26 UTC