Closure-compiler: Add transpilation support for async and await

[ChadKillingsworth]

Async functions are now a stage 3 proposal of ES7: http://tc39.github.io/ecmascript-asyncawait/

Async functions are now supported via a flag in Edge: https://blogs.windows.com/msedgedev/2015/09/30/asynchronous-code-gets-easier-with-es2016-async-function-support-in-chakra-and-microsoft-edge/

Transpilation is usually to an ES6 generator: https://babeljs.io/docs/plugins/transform-async-to-generator/

[dimvar]

FYI, we plan to support this, but it won't happen in Q1 for sure.

[SunboX]

:+1:

[SunboX]

It's also possible to transpile async/await to Promises like this:

In

async function test() {
  await db.destroy();
}

Out

function test() {
  return Promise.resolve().then(function () {
    return db.destroy();
  }).then(function () {});
}

_Source: https://github.com/marten-de-vries/kneden_

[ChadKillingsworth]

I specifically want the generator method - not promises. It is simply way too easy to swallow exceptions in non-trivial cases. See #1515

[metrofun]

Is there are any progress on it?
Btw I am trying to _sell_ Closure Compiler (Google Traceur) to my team and without async/await it's a bit difficult with Babel nowadays :sweat_smile:

[Dominator008]

@metrofun Thanks, but FYI, Closure and Traceur are two different compilers :)

[metrofun]

@Dominator008 My bad, I was sure Closure Compiler uses Traceur under the hood. Just to clarify then, I'm trying to _sell_ Closure Compiler ;)

[MatrixFrog]

It _may_ happen this quarter but I make no promises.

[blickly]

This missed the deadline for ES7 (== ES2016), so now the earliest this could be standardized is ES8.