Package cannot be imported in TS project compiled with NodeNext

[Josh-Cena]

While working on facebook/docusaurus#7586, eta was one of the packages blocking a successful compilation.

To Reproduce

yarn add typescript eta

tsconfig.json:

{
  "compilerOptions": {
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "strict": true
  }
}

Add a TS file with:

import eta from "eta";

It errors: "Could not find a declaration file for module 'eta'. 'node_modules/eta/dist/eta.cjs' implicitly has an 'any' type."

The reason is because eta's package.json exports does not have a types field for each entry, so TS can't associate the js files with their types. (Before, TS would always use the root types entry).

Fixing this is a bit involved, because the package also has "type": "module", which causes the .d.ts files to be interpreted as ESM. Therefore, even for .d.ts files, explicit extensions are required. I'm not sure what the best way to fix this is, so I just want it to be in your backlog first.

Expected behavior

Successful TS compilation

Package & Environment Details

• Environment: Node 18.3.0
• Version: 1.12.3

Additional context

There's some basic writeup here: https://devblogs.microsoft.com/typescript/announcing-typescript-4-7/#package-json-exports-imports-and-self-referencing I can't find a more comprehensive guide.

[nebrelbug]

@jakubmazanec just added a "types" field to the exports entry in package.json, but I'll leave this open because the exports field needs some more substantial changes.

[nebrelbug]

@Josh-Cena this should be working now!