Fix Issue #39155 (importModuleSpecifierEnding does not apply for module specifier completions)

[Simar-B]

Fixes #39155

[ghost]

All CLA requirements met.

[andrewbranch]

Looks good, thanks!

[Simar-B]

My pleasure!

[AlCalzone]

@andrewbranch this does not seem to have any effect for me in TypeScript 4.3. With

	"javascript.preferences.importModuleSpecifierEnding": "js",
	"typescript.preferences.importModuleSpecifierEnding": "js",

TypeScript defaults to importing a .ts file and then complains that the import may not end in .ts:

[silkfire]

Why are you storing TypeScript code in .js files?

[AlCalzone]

I'm not. #33079 and https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c#how-can-i-make-my-typescript-project-output-esm for some context

[silkfire]

These are two separate things. If you don't want the linter to complain you need to set that in the settings, so the TS Server knows what extensions you are expecting in your imports.

[AlCalzone]

Did you even read my first comment? I've set the setting to use a js extension, but TypeScript adds a ts extension instead. It then complains about the ts extension and proposes a js extension, which is what I've wanted anyways.

Side note: It would be even better to not have to deal with this, but we'll have to wait for the TypeScript team to finalize the ESM support for that.

[silkfire]

I'm sorry, I didn't mean to misunderstand you. That must surely be a bug as specifying "js" should not result in a spurious .ts extension being suggested by TS for files that aren't even TypeScript files.

I see, what would the upshot of that be?

[AlCalzone]

in a spurious .ts extension being suggested by TS for files that aren't even TypeScript files.

They are TypeScript files. But importing them with a .js extension is currently the recommended way to do ESModules, because TypeScript does not yet change the extension during compilation. So we need to specify the filename the file is going to have at runtime, which is also why TS suggests using a .js extension.

[andrewbranch]

@AlCalzone I believe you’re describing #44374, fixed by #44602.