Reflect

[Victorystick]

The Reflect global is, as far as I know, a part of the ES6 spec. I was a bit surprised not to find it in the es6-shim. Is there any reason as to why it isn't? If not, I'd consider giving it a go.

I'd like to use this PR to discuss Reflect implementation.

[ljharb]

The vast majority of the things on Reflect simply can't be shimmed, as I recall - it needs to support Proxies, Symbols, etc - all sorts of unshimmable things.

I'm happy to add it if: a) everything we provide on it is 100% spec-compliant b) No engine implements Proxy, Symbol, etc before implementing any applicable Reflect methods c) Somebody testing for the presence of global Reflect won't run into trouble with only some of the methods defined. d) It works cross-realm in the appropriate fashions (which iirc is just iframes atm)

Is there any JS engine that's implemented any part of Reflect yet?

[ljharb]

I stopped halfway through the tests because it seems like you wanted to discuss the PR before adding the rest of them - this is awesome, and I really appreciate the work you put in!

Let's make sure we've fleshed out consequences here in this thread first, but let's proceed with the goal of merging this ASAP in mind :-)

[ljharb]

@zloirock thanks, good call!

[Victorystick]

Looking at ES6 Compat table, it seems that Reflect has been implemented at least partially by the IE team in their Technical Preview and by EchoJS.

[ljharb]

Awesome, when I do my testing, I'll test with IE 11 as well.

[Victorystick]

Reflect is getting more or less done. Time for another look?

[ljharb]

Sweet, will take another look today!

[ljharb]

@Victorystick OK, I think all the things I commented on are minor, the biggest being that both the es6-shim and its tests need to run all the way down to ES3 browsers, so everything that's not shimmable in ES3 or ES5 needs to be feature-detected at runtime. Almost there :-)

Thanks, this looks awesome! I'm excited to merge this (after the changes above, and after I do some cross-browser testing)

[Victorystick]

Have you also noticed that the Travis CI builds often fail because sh: 1: jscs: not found?

[ljharb]

Yes :-/ that's an issue with jscs's dependency tree. For now I just manually restart those builds and they pass eventually.

[ljharb]

I think I'm primarily waiting for bindContext to be removed before a final rereview and merge.

[ljharb]

OK, we're down to the primary blocker being that any Reflect method that can't work in ES3 (ie, ones that use property descriptors, or setPrototypeOf, etc) need to be conditionally added.

Thanks a lot for being persistent on this, this is going to be great to have!

[zloirock]

Latest spec draft adds newTarget argument to Reflect.construct. It can't be fully polyfilled, but result should be created from newTarget.prototype.

[ljharb]

Anything that can't be fully polyfilled in any engine needs to go in the es6-sham, not the es6-shim. However, if it can be fully polyfilled in true ES5 engines (via Object.create) then that's great

[Victorystick]

I set out with the intention of polyfilling Reflect in an ES5 environment, since it is so dependent on the Object property methods.

[ljharb]

OK - so this looks good to go, as long as it's freshly rebased on top of the latest master! ( ﾟ◡ﾟ)/

Followup item is to pull as much Reflect functionality as possible into ES3 engines.

[Victorystick]

This should be it. :+1:

[ljharb]

@Victorystick It looks great and I'm ready to merge it, but I still see a merge commit (37e8818db3b4e03a9b341106381db9a1cc38b012) - can you do a rebase onto latest master (as opposed to a merge with latest master)?

[ljharb]

I'm anxious to merge this, so unless you're already in progress I'll make a new branch and rebase it myself (your name will remain on all the commits).

[ljharb]

Merged via dd6b1b254fb6e08045a9f0bdce3620457581528f

[ljharb]

Thanks so much for contributing this, and working through all the back and forths with me!

[Victorystick]

No worries. Thank you!