Change tsconfig/json moduleResolution to bundler

[ConProgramming]

Describe the problem

To reiterate this issue: In TypeScript 4.7, along the property "module": "node16" that enables ESM features in TypeScript, there are new values for the property "moduleResolution": "node16" and "nodenext". Both values allows importing from dependencies with package.json exports, imports, and self-referencing.

Right now, this property in the default .sveltekit/tsconfig.json is "node." This doesn't support features like defining "types" in "exports".

Describe the proposed solution

Change tsconfig/json moduleResolution to node16 or nodenext. This will mean that relative import paths need explicit file extensions - so './$types.js'; instead of './$types';, and similar changes. It'd be a breaking change, atleast for typescript linting, but seems to be more future proof.

Alternatives considered

Keep moduleResolution as node. It's less future proof, as we'll keep having to use declare module and a global types property in package.json.

Importance

nice to have

Additional Information

No response

[david-plugge]

Agree!

But in case you really need this today make use of typesVersions

{
	"exports": {
		".": {
			"types": "./dist/index.d.ts",
			"default": "./dist/index.js"
		},
		"./component": {
			"types": "./dist/component.d.ts",
			"default": "./dist/component.js"
		}
	},
	"types": "./dist/index.d.ts",
	"typesVersions": {
        "*": {
            "component": [
                "dist/component.d.ts"
            ]
        }
	}
}

https://www.typescriptlang.org/docs/handbook/declaration-files/publishing.html#version-selection-with-typesversions

[ydcjeff]

With moduleResolution nodenext, what would we use instead of declare module?

[dummdidumm]

We won't be changing moduleResolution to next/node16 because it has lots of unpleasant side effects:

• all relative imports now need the full path and file extension (and it's weird because you need to import TS files with a .js ending)
• not properly built packages will suffer because their types are no longer resolved

Instead we should leverage TypeScript 5.0's upcoming moduleResolution: "bundler".

Changing this is a breaking change though (at least for create-svelte)