Add TS types

[vdegenne]

This commit adds TypeScript types to get rid of error such as :

Plugin typescript: @rollup/plugin-typescript TS2307: Cannot find module './test.css' or its corresponding type declarations.

@changesets/cli package was also added to the project to ease up external contribution.

[JulianCataldo]

I encountered the same situation and thought of monkey-patching the fact that TS still not support assert or with with CSS (JSON works though) microsoft/TypeScript#46689

Didn't tested your solution yet,
but assuming Vite is using ambient modules for foo.css?inline, etc., in a similar manner, we would lose an important DX feature in my eyes:
Cmd+Click to the CSS file.
With types, it will always point the same .d.ts, like with the newest Vite.

So it's a trade-off I guess ;) At least, if we keep the refactoring support, while shutting down TS complaint, it would still be a better situation.

Thx!

[vdegenne]

@JulianCataldo Nevertheless I think it's superior to Vite, the extra ?inline provokes VSCode to travel directly to the declaration file, whereas this solution will also bring the CSS file into light :

I wonder how long we still have to wait until TypeScript decides to support these imports natively, and if VSCode has an option to ignore specified declaration files.

[vdegenne]

@justinfagnani Can you review this one? Thanks

[JulianCataldo]

Need to point the the class prototype, though

---

Before:

---

After:

env.d.ts:

declare module '*.css' {
	export default CSSStyleSheet.prototype;
}

declare module '*.scss' {
	export default CSSStyleSheet.prototype;
}

---

Unrelated note: I do a transform / replace from .scss to .css before the TS is compiled to JS to the dist. But that's in my build sauce. I do that for keeping a handy CMD + Click to the source SCSS file while in dev.

[vdegenne]

@JulianCataldo Have you tried this syntax instead? which is the PR I proposed.
You can't directly return a type

[JulianCataldo]

Awesome! I was fiddling with const, var, default,… but couldn't recall the exact pattern, even though I'd seen it somewhere before. Thx