[file-extension-in-import] Does not work properly in TypeScript projects with allowImportingTsExtensions

[Zamiell]

Environment

Hello,

With the following config:

"n/file-extension-in-import": ["error", "always"],

Will autofix this:

import { foo } from "./foo";

To this:

import { foo } from "./foo.js";

However, this is a bug in TypeScript projects that use allowImportingTsExtensions. In such projects, having a ".js" import is a bug, because the assumption is that our entire application is written in TypeScript, and no JavaScript files will probably ever exist.

Proposal:

Instead of fixing to .js, the rule should auto-fix to .ts when the "tsconfig.json" has the allowImportingTsExtensions option set to true.

What rule do you want to report?

file-extension-in-import

Participation

• I am willing to submit a pull request for this issue.

[scagood]

🤔 This makes sense, I will try to look next week. Thanks for the report!

[Zamiell]

@scagood I see that you've fixed the bug on your fork, good work! Anything I can do to move this issue along?

[scagood]

There are two things holding this back:

1. I need to make some fixes (in feat!: Start using enhanced-resolve to improve ts support #139) specifically it looks like I may have broken the file-extension-in-import rule.
2. We want to wait for eslint v9 to be released so we're sure that the plugin is stable with that release before we introduce some possible breaking changes.

I should get some time on Thursday to look into the broken rule problem.