[import/extensions] Option to enforce extensions for type-only imports

[trevor-scheer]

We have a use case for enforcing the .js extension even on type-only imports (I'm aware this is odd).

This requirement stems from supporting TS users using modules (by specifying "type": "module" in their package.json) and specifying nodenext for moduleResolution options in their tsconfig.

Some context can be gleaned from this PR, where I created a failing test using ^this configuration and proceeded to resolve the errors by adding .js extensions to type-only imports.
apollographql/apollo-server#6731

Related: #2270

Does another option seem reasonable to enforce extensions on type-only imports as well? I'd be happy to open a PR to introduce this if so.

[ljharb]

Duplicate of #2111, i think.

It seems overwhelmingly horrific to add a .js extension when it's not even JS that's being imported, so I don't think it's reasonable to do that. Perhaps the TS import resolver could handle it, but that shouldn't be part of the main plugin. cc @JounQin

[JounQin]

Handle what? The ts resolves .js as .ts correctly, What can I do in the resolver?

See also #2111 (comment)

[trevor-scheer]

While I don't disagree (re: overwhelmingly horrific), it looks like this is the world TS users are in for, as some others in #2111 have pointed out. I've gotten some context reading through #2111, but some things are still fuzzy.

IIUC, the PR I referenced, while related, is right to ignore type imports because import/extensions is not interested in (but is generally compatible with) typescript specifics. That's probably grounds for closing this issue, possible duplicate aside.

This comment #2111 (comment) seemed to be interesting to folks, though I'm not sure there's agreement there and conversation seems to have gone in a slightly different direction. Is there some consensus around the end of the conversation there but just waiting for someone motivated to take action?

@JounQin is the reference to the comment directed to me or @ljharb? I don't think it's particularly interesting to me, but there's a lot I don't know yet about eslint plugins.

@ljharb best next step? I'd guess offering my assistance on #2111, mostly asking in case I've misunderstood anything.

[mxdvl]

As moduleResolution:"bundler" and allowImportingTsExtensions are available since TS 5.0, it would be even more important to support enforcing extensions from type imports.

[bodinsamuel]

Hey team, do we have an update on this or an alternatives solution? ☺️