TypeScript infrastructure

[dsevillamartin]

Will probably want to include some shims

Old example shims in WIP rewrite branch

https://github.com/flarum/core/blob/4c8af1cdf876b9bd3770f76c33eb6c9ac80608f0/js/webpack-flarum-shims.d.ts#L7-L17

https://github.com/flarum/core/blob/4c8af1cdf876b9bd3770f76c33eb6c9ac80608f0/js/shims.d.ts#L3-L7

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• Webpack config is temporarily in this PR to avoid weird NPM garbage & publishing buggy flarum-webpack-config release
  • See Add TypeScript support flarum-webpack-config#3

[askvortsov1]

@datitisev perhaps we should have this PR be just the setup of Typescript infrastructure, and follow up with the actual typescript changes in a second PR? And merge the first one in now?

Also, agree about putting in the shims 👍

[dsevillamartin]

@askvortsov1 Ok, done.

EDIT: I won't put the shims here. They aren't necessary (though they do help with typings, but more when typing Mithril stuff so lets wait for mithril v2 there maybe? idk)

[franzliedke]

Thanks, looks good! Can we undraft this to get it merged?

Just one question: what's the purpose of @babel/plugin-syntax-dynamic-import?
Okay, I kinda understand that from its description on NPM, but how is it related to TypeScript?

[dsevillamartin]

I... don't know what that does. I copied it over from my Mithril branch. Looking at the babel docs for that package did not help in understanding. I think it has something to do with import() functions (not import statements) returning Promises..?

[franzliedke]

Yeah, those allow you to import scripts at runtime, I don't think that's needed for TypeScript at all. Please remove that, then we can merge. 🤗

[franzliedke]

Thanks a lot! TS-ing "comon" and "admin" should now be safe. (One file in "common" is changed in #2161, but we will manage.)