Improve babel integration

[s-panferov]

Hello. I am developing https://github.com/s-panferov/awesome-typescript-loader and I decided to implement a feature to pick-up precompiled files for .ts modules if any. I need this to speed-up TypeScript + Babel use-case, because this pair is really slow on a big codebases. Unfortunately, atom-typescript externalTranspiler functionality has several issues:

1. There is no way to pass options into Babel.
2. There is no way to use .babelrc file, because filename property is not passed into babel options and babel doesn't know where to look for the .babelrc file.
3. Generated source maps are possibly incorrect, because I get an error while using them in my workflow:

RROR in ../arui/src/icon/common/icon.tsx
Module build failed: Error: No element indexed by 1
    at ArraySet_at [as at] (/Users/panferov-s/Workspace/arui-nyc/node_modules/react-hot-loader/node_modules/source-map/lib/source-map/array-set.js:83:11)
    at SourceMapConsumer_parseMappings [as _parseMappings] (/Users/panferov-s/Workspace/arui-nyc/node_modules/react-hot-loader/node_modules/source-map/lib/source-map/source-map-consumer.js:225:44)
    at SourceMapConsumer.Object.defineProperty.get (/Users/panferov-s/Workspace/arui-nyc/node_modules/react-hot-loader/node_modules/source-map/lib/source-map/source-map-consumer.js:160:14)
    at SourceMapConsumer_eachMapping [as eachMapping] (/Users/panferov-s/Workspace/arui-nyc/node_modules/react-hot-loader/node_modules/source-map/lib/source-map/source-map-consumer.js:455:24)
    at Function.SourceNode_fromStringWithSourceMap (/Users/panferov-s/Workspace/arui-nyc/node_modules/react-hot-loader/node_modules/source-map/lib/source-map/source-node.js:78:26)
    at Object.module.exports (/Users/panferov-s/Workspace/arui-nyc/node_modules/react-hot-loader/index.js:87:16)
 @ ../arui-nyc/src/icon/icon.ts 20:29-65

I've fixed all the stuff in this PR. All useful changes are in the first commit. Please take a look.

Related issues:

#521 Implemented
#522 Hacked locally by adding typescript.d.ts into tsconfig.json by hand, but I think that it is not a good solution, so I don't include compiled files into this PR.

[basarat]

Marked as breaking change as it changes a key in tsconfig.json

[basarat]

Marked as breaking change as it changes a key in tsconfig.json

I see that you tried to maintain backward compat. Thanks 🌹

[basarat]

I am okay with this. But since I don't use it personally, would like a review by @nycdotnet 🌹

[s-panferov]

@basarat

I see that you tried to maintain backward compat. Thanks 🌹

Yes. The first thought was to write such type:

externalTranspiler?: string | { name: string; options?: any };

It looks more self-describing, but leads to type guards or ugly type-casting inside building.ts. I can return the variant, if you want proper-looking types.

[basarat]

I can return the variant, if you want proper-looking types.

That would be better please 🌹 don't want magic meanings :)

[s-panferov]

@basarat

Union type and type guard for externalTranspiler: https://github.com/s-panferov/atom-typescript/commit/87bc64f69616b2d33d06bee0a1fe2069a94d685e

All three cases tested locally:

1. With string value
2. With object value without options
3. With object value with options

[basarat]

Thanks v5.3.0 🌹

[nycdotnet]

Thanks. I know this was merged already, but I will take a look at this soon. I'm a bit busy at the moment due to the birth of my son. :-)

[nycdotnet]

Was pretty straight-forward. Nice job.

[johnnyreilly]

Congratulations @nycdotnet!!!! Hope all is well

[nycdotnet]

Thanks. :-) Mom and baby are good.

[johnnyreilly]

Excellent! Yourself? I'm guessing: tired (I was this time last year)

[basarat]

@nycdotnet 👶 🌹