TS types output

[chandlerprall]

Summary

supports #1262

• removes src from published code
• collates all types from .t.ds,.ts, and .tsx from src into a top-level eui.d.ts file for publishing
• introduces a top-level types directory which is git- and npm-ignored, this allows the typescript binary to have a place to emit definitions & transpiled files, as turning emit off creates other problems.

Tested by linking EUI into kibana and modifying the new eui.d.ts file. I also removed the src directory in the linked build to ensure it was no longer used.

This relies on dts-generator for the dirty work of combining all definitions into the top-level eui.d.ts. The implementation on this branch (scripts/dtsgenerator.js) is overkill but is the correct setup to allow authoring pure typescript files. The changes in this PR are pulled over from my in-progress typescript branch (https://github.com/chandlerprall/eui/tree/feature/typescript) which uses this setup to support both existing .d.ts and .tsx files.

Checklist

- [ ] This was checked in mobile
- [ ] This was checked in IE11
- [ ] This was checked in dark mode
- [ ] Any props added have proper autodocs
- [ ] Documentation examples were added

• A changelog entry exists and is marked appropriately
  - [ ] This was checked for breaking changes and labeled appropriately
  - [ ] Jest tests were updated or added to match the most common scenarios
  - [ ] This was checked against keyboard-only and screenreader scenarios
  - [ ] This required updates to Framer X components

[pugnascotia]

Sorry, clicked close by mistake.

Anyway, the code looks reasonable. I ran the build and it created eui.d.ts as expected. I couldn't see the types directory, does that get cleaned up somehow?

I noticed that there are still triple-slash directives in eui.d.ts - might that be a problem? It's confusing if nothing else, because the file paths in the directives are wrong.

[chandlerprall]

The types dir isn't cleaned up - by removing noEmit": true most times the tsc compiler is executed it writes to types. My IDE's typescript integration is one thing that triggers it. Ideally it shouldn't really be a thing; I haven't yet found a way to guarantee avoiding all the ways it gets created.

I'll double check that the triple-slash references aren't a problem, or if they can be excluded from the generated file.

[chandlerprall]

@pugnascotia the /// <reference lines weren't effecting anything, but I've updated the dtsgenerator script to remove them after building to keep it clean.

[pugnascotia]

Run the result through prettier?

/ducks

Joking, LGTM.

[jasonrhodes]

LGTM too, I notice that the jsdoc style comments are imported in and then show up in VS Code.

The path for the @see annotation is possibly a bit confusing but I'm not sure there's a) much to do there easily and b) if it would even be helpful to update the path. As long as that's expected, I say 🚢 🇮🇹