Typescript extractor

[huan086]

Resolves #151 by using typescript to output ES2016 to preserve tagged template literal, and to preserve JSX. The result is then passed to existing lingui transforms and extract.

Known issues: typescript currently supports new features like fragment syntax <>children</>, but these are only supported in Babel 7. Thus the extractor cannot parse files using the new features. I'm not sure if we should upgrade to Babel 7 (still in beta) to solve this.

[huan086]

One more thing, no idea where to write unit test for this

[tricoder42]

@huan086 Thank you for this PR! Great work!

Babel 7 will be used in next major version (3.x). Right now it's used in master branch, but I haven't merge stabel-2.x for a while. I'll take a look. Would be great to keep these two branches as close as possible so we can release 3.x once Babel 7 becomes officially available.

For the unittests, I would put then in src/api/extractors/typescript.test.js, but atm I have no idea how to write them.

[huan086]

Currently writing the Typescript definitions and submitting them to DefinitelyTyped. Facing difficulties for @lingui/react because the react types are quite hard to understand.

After the typings are done, I'll be able to write the unit tests without typescript complaining about xxx is not a module.

[tricoder42]

This looks solid! Would you be interested in updating Typescript guide? Is there any special setup required to make typescript work or is it enough to install @lingul/cli and run lingui extract?

[huan086]

No special setup needed. The original typescript implementation already did all the groundwork 😊

[tricoder42]

Awesome! 👍

[tricoder42]

Fixed and released in v2.2.0. Thanks to all involved!