Implement Async Generators

[bterlson]

Proposal is here: https://github.com/tc39/proposal-async-iteration
Basic idea is a combination of an async function and a generator - essentially a generator you can await within.

There are already a number of test262 tests and v8 has an implementation we can compare against.

[zbraniecki]

SpiderMonkey also has it implemented - https://bugzilla.mozilla.org/show_bug.cgi?id=1331092

[benjamingr]

Any update on this?

[bterlson]

@benjamingr I have no update to share yet, but I'll be sure to update this issue (and the roadmap) when I do!

[zbraniecki]

This has been accepted into ES2018. With support in SpiderMonkey, V8 and jsc, it would be great to get this in ChakraCore soon.

[rektide]

I don't know ChakraCore teams standard practice, but it would be SUPER HELPFUL to have a Platform Status thing to track.

[BobChao87]

@rektide Are you perhaps looking for Edge's Platform Status?

Unfortunately, it looks like the async iterators/generators/loops aren't quite there yet, but overall it's a very good resource.

[rhuanjl]

Is there any update on this feature/plan for when it will be implemented?

[ciscoo]

@rhuanjl See the link posted by @BobChao87

It is currently marked as UNDER CONSIDERATION and:

Roadmap Priority: High — We intend to begin development soon.

So to answer your question, no idea when really, but soon. 🤷‍♂️

[rhuanjl]

@ciscoo the platform status isn't exactly up to date also it's Edge not Chakracore - features make it to CC some time before they make it to edge.

For 2 e.g.s of not up to date:

1. Promise.prototype.finally per Edge platform status is in development BUT - it's fully functional in chakracore 1.10 (see PR 3520).
2. Object rest/spread - per Edge platform status is under consideration BUT - it's actually experimentally implemented in CC - supported but behind a flag so should at least say in development.

[falsandtru]

Why does no one still implement or schedule this feature?

[rhuanjl]

Would an external contribution be welcome here?

(Not certain I could manage this but could give it a try if an external PR would be welcome)