Convert to TypeScript

Based on the discussions around #121 and the test we just merged in #662, we are going to convert theme-ui to TypeScript! 🎉 The plan is to go package-by-package and gradually move all .js files to .ts files.

As you can see there is a fair amount of packages to convert, so we would love your help! 💪

Here is how to convert a package (take a look at #662 for an example):

1. Add the --tsconfig tsconfig.json option to the “prepare” and “watch” commands in the package.json and copy the tsconfig.json from the core package.
2. Add "types": "dist/index.d.ts" and "source": "src/index.ts" to the package.json
3. Go file-by-file, rename them from .js to .ts and fix all type errors and any types in the generated typedef (dist/index.d.ts).
4. Submit a PR and tag me as a reviewer!

To avoid duplicate work please comment which package you want to work on (as long as nobody else is also working on it) so we can mark it as taken.

Packages that still need to be converted:

• chrome (#909)
• color (#672)
• color-modes (claimed)
• components (https://github.com/system-ui/theme-ui/pull/692)
• core (#662)
• css (#672)
• custom-properties (#671)
• editor (#900)
• match-media (#696)
• mdx (#703)
• preset-base (#675)
• preset-bootstrap (#694)
• preset-bulma (#694)
• preset-dark (#694)
• preset-deep (#694)
• preset-funk (#694)
• preset-future (#694)
• preset-polaris (#694)
• preset-roboto (#694)
• preset-swiss (#694)
• preset-system (#694)
• preset-tailwind (#694)
• preset-tosh (#694)
• presets (#694)
• prism (#805)
• sidenav (#917)
• style-guide
• tachyons (https://github.com/system-ui/theme-ui/pull/691)
• tailwind (https://github.com/system-ui/theme-ui/pull/686)
• theme-provider (#708)
• theme-ui (#724)
• typography (#890)

These packages will be handled separately (see #950)

• gatsby-plugin-theme-ui (#705)
• gatsby-theme-code-recipes (#709)
• gatsby-theme-style-guide
• gatsby-theme-ui-blog (#711)
• gatsby-theme-ui-layout (#710)

[hasparus]

@MarcStdt 0.4.0 is not released yet (you can use next tag or 0.4.0-rc.X versions), but the conversion already happened, and the release should happen in the nearest future.

[jxnblk]

@hasparus @mxstbr – my understanding is that Gatsby’s current TS support does NOT work for plugins and themes yet, and as you stated, we do not want to break compatibility with earlier Gatsby versions. I think how we want to handle TS versions of Gatsby plugins is probably worth a bigger discussion, and I think we should move that to a new, separate issue. I’d suggest keeping the in-flight PRs for those packages open, but cut a 0.4 release without those, and addressing those for v0.5. Does that sound reasonable to everyone?