[no-missing-imports]: add tryExtensions option

[piranna]

Similar to https://github.com/mysticatea/eslint-plugin-node/blob/master/docs/rules/no-missing-import.md, add support for the tryExtensions option.

[aladdin-add]

if using esm, technically it's a bug to use "tryExtensions" - the ext is always required, just like the web.

to support the nodejs esm, we have removed the option in d24be36.

[piranna]

ESM requires to have extensions always, and I agree on that, but Typescript on the other hand forbids them, so without extensions, files are not found...

[aladdin-add]

well, we could reintroduce the option to support something like ts.

[piranna]

that would be really nice :-) Maybe disabled by default, enforcing extensions to be added.

[jordanbtucker]

ESM requires to have extensions always, and I agree on that, but Typescript on the other hand forbids them, so without extensions, files are not found...

@piranna Can you clarify what you mean? TypeScript allows you to have extensions in your module specifiers because it just copies them verbatim.

import util from './util.js'

transpiles to

const util = require('./util.js')

So you shouldn't use .ts file extensions in module specifiers like this.

import util from './util.ts'

because it just transpiles to

const util = require('./util.ts')

which breaks because Node.js and browsers can't parse TypeScript.

Note that you can still have a util.ts file, you just need to import it as if it is a .js file that exists relative to the transpiled .js file that will be importing it. TypeScript will import the .d.ts file for that .js file and everything works.

[piranna]

@piranna Can you clarify what you mean? TypeScript allows you to have extensions in your module specifiers because it just copies them verbatim.

Yes, but that feels like a nasty hack, because in source code there's no .js files, only .ts ones, being the .js just only on the transpiled code, so this plugin will also fails because there's no .js files at all on source files. Correct solution should be Typescript following ESM rules and allow to have .ts extensions on imports, but that's not the case. So, the alternative is to have back the tryExtensions option, and set it to .ts files.

[jordanbtucker]

Thanks for clarifying. I agree that adding the tryExtensions option for imports will fix the vast majority of use cases for TypeScript users.

[Lioness100]

Any progress on this? I'm using --experimental-specifier-resolution=node flag, which allows for extensions to be omitted in esm, which is breaking this rule.

[ashercoren]

@aladdin-add Any progress on this?

[uiolee]

I'm experiencing the same issue. It is blocking me from migrating from eslint-plugin-node to eslint-plugin-n.

[scagood]

mmm, it looks like this is supported from the settings block, but not from the rule's option 🤔

https://github.com/eslint-community/eslint-plugin-n/blob/master/lib/util/visit-import.js#L35

So this in theory is as simple as adding tryExtensions: getTryExtensions.schema here:
https://github.com/eslint-community/eslint-plugin-n/blob/master/lib/rules/no-missing-import.js#L31