Linter plugins: Support plugins written in TypeScript

[overlookmotel]

We should support linter plugins written in TS.

We can provide types for defineRule (#13945) and definePlugin (#14008) to give TS support when writing custom plugins.

But what's the best way to add TS support?

1. Rely on NodeJS's built-in type-stripping support? (and user has to use a NodeJS version that supports that)
2. Use a library? (which one?)

Any thoughts?

[Sysix]

Any thoughts?

The ESLint Config Resolver is using jiti to load typescript files:
https://github.com/eslint/eslint/blob/448b57bca3406ee12c4e44e9298fc0c99d3ee10c/lib/config/config-loader.js#L133-L175

I think Vite uses the same for its config too.
@oxlint/migrate uses it too oxc-project/oxlint-migrate#109

I requested for @oxc-node something similar: oxc-project/oxc-node#173

Note: Bun and Deno supports TS out of the box

[overlookmotel]

Thanks for the suggestion @Sysix. In the absence of support in oxc-node, it looks like Jiti is the best option.

[ArnaudBarre]

Vite bundles via esbuild (and rolldown in vite-rolldown) which allows to watch all imported files to auto-restart on config change (and for ex you defined a plugin into another file)

[overlookmotel]

Are you suggesting we add Vite as a dependency of Oxlint to bundle JS plugins before executing them? (this feels like rather a heavyweight solution!) Or are you saying the user should use Vite?

Obviously, we'd expect JS plugins published on NPM to be compiled from TS to JS before publishing. Supporting TS is for the benefit of users who have custom Oxlint plugins in their own repo, and want to write them in TS.

Maybe we should just say that's only supported on versions of NodeJS which support type-stripping (22.18.0+) and avoid the overhead of Jiti? 🤔

[ArnaudBarre]

Neither! What I'm saying is that Vite is not using jiti to load the config but a native bundler which brings two benefits:

• Faster than Babel used by jiti (but will be noticable only if you have 10+ custom rules I think)
• You get back a list of files used by the configuration, that you can then watch to relint the project on file change

With node supporting TS natively, I think using jiti is an overhead for very few users that will want the latest linter but wants to use node 20.

Using rolldown to get sub files config watching can be a nice to have, and given that rolldown seems to be only 1mb it doesn't cost of install size

[overlookmotel]

#14163 exports types from oxlint and adds tests for running plugins written in TS on a version of NodeJS that supports type-stripping. Seems to work.

[overlookmotel]

Neither! What I'm saying is...

OK, I'm probably being a dumb-ass, but I still don't get exactly what you're proposing. Include rolldown as a dependency of oxlint and use it to compile plugins on demand? Or are you saying there's some useful pattern using a bundler that we could suggest to users to get "hot reloading" while developing plugins?

Using rolldown to get sub files config watching can be a nice to have, and given that rolldown seems to be only 1mb it doesn't cost of install size

Personally I'm less concerned about the install size than the extra time cost to bundle plugins. I assume type-stripping is faster than bundling.

[ArnaudBarre]

Ahah I've seen your PRs, I would not say that 😄
Yes I'm saying that including rolldown as a dependency to get some kind of hot reloading of the config (for IDE usage) can be a nice feature.

But yes native type stripping will be faster in almost all cases. @sapphi-red found some hack to get both but this is using things which would brake in Bun or Deno I think: vitejs/vite#19374 (not merged though)

[sapphi-red]

I listed the limitations of each approach in vitejs/vite#20162 (jiti has the same limitation with --config-loader=runner, but probably slower due to the use of babel).
I think using the native type-stripping is good enough for the initial implementation. There are some minor downsides, but it is the most easy way.