Parcel 2: TypeScript Transformer

[DeMoorJasper]

↪️ Pull Request

TS Transformer ported from Parcel 1 to Parcel 2

Not sure if we actually wanna implement it this way though, as Babel now supports TS and it would probably be a bit faster to create and transform the ast using babel/ts

Perhaps we should have both?

💻 Examples

🚨 Test instructions

✔️ PR Todo

• Added/updated unit tests for this change
• Filled out test instructions (In case there aren't any unit tests)
• Included links to related issues/PRs

[mischnic]

TS Transformer ported from Parcel 1 to Parcel 2

Not sure if we actually wanna implement it this way though, as Babel now supports TS and it would probably be a bit faster to create and transform the ast using babel/ts

One major misconception in the past was that Parcel doesn't do typechecking, I guess this won't be changed?

[DeMoorJasper]

@mischnic Parcel doesn't do typechecking. However it would be cool to have this feature in Parcel 2, that's the only reason I can think of to use ts-compiler

[devongovett]

@fathyb what do you think? I know people have been asking for better typescript support, and one of those asks is support for actual type checking. I kinda think that type checking and linting (e.g. eslint) could be handled in a similar way: we compile synchronously, but type check/lint in the background. That way you don't have to wait as long for builds when you're just hacking, but have the type checking/linting information available if you want it. Thoughts?

[mischnic]

Coming from #2039, Parcel 1 basically ignored the target and module option in tsconfig.json.
I think it would be better for performance and DX to not run Babel after Typescript (by default), so that these option actually work (at least target, no sure about module).

[timfish]

Just be aware that if you use Babel with separate type checking, there is currently no support for:

• const enum
• emitDecoratorMetadata not supported out of the box