fix(js): CJS build with nodenext

[alexandre-abrioux]

Issue

In CommonJS projects that use nodenext or node16 as moduleResolution, importing the @bonfida/spl-name-service library is impossible. We encounter the following error:

error TS2305: Module '"@bonfida/spl-name-service"' has no exported member [... name of the module ...]

The issue is also described in #105.

Context

With nodenext and node16 for moduleResolution—which is now the value recommended by TypeScript as classic and ndoe10 are deprecated—TypeScript interprets dist files dependending on their extension (.cjs/.d.cts/.mjs/.d.mts), or depending on the library's type (commonjs/module) for .js/.d.ts dist files.

Cause

@bonfida/spl-name-service exports JavaScript files with correct extensions (.cjs/.mjs), but the types are only exported as .d.ts, so can only be interpreted as ESM because the library's type is module.

sns-sdk/js/package.json

Line 8 in 42a058f

"type": "module",

This explains why TypeScript cannot load @bonfida/spl-name-service in a CommonJS project with nodenext and node16 for moduleResolution.

You can verify the issue by using the arethetypeswrong tool available at this URL:
https://arethetypeswrong.github.io/?p=%40bonfida%2Fspl-name-service%403.0.11
(see the "Masquerading as ESM warning")

Solution

To keep it simple, everything is now exported as .js/.d.ts in their respective directory (dist/esm and dist/csj). For CommonJS, we create a simple dist/cjs/package.json file that contains the following:

{
  "type": "commonjs"
}

; this way, both the source code and types are interpreted correctly.

Here is the result of arethetypeswrong after the change:

Reference

• This solution is described here in a GitHub issue about dual packaging on the TypeScript repository: Feature Request: allow change file extension of generated files from .ts  microsoft/TypeScript#49462 (comment)
• This solution is also used in the more popular tsconfig-to-dual-package tool, which offers a way to achieve the same result with two tsconfig.json files and a specific CLI.
• Keeping types next to dist files (vs. having them in a separate directory) is recommended by maintainers of TypeScript.