Library is not consumable from CJS context in TypeScript application

[IdkMan2Usertive]

🐛 Bug Report

Library cannot be consumed from the CJS context when using TypeScript as of TS1479 error:

TS1479: The current file is a CommonJS module whose imports will produce 'require' calls; however, the referenced file is an ECMAScript module and cannot be imported with 'require'. Consider writing a dynamic 'import("i18next-fs-backend")' call instead.   To convert this file to an ECMAScript module, change its file extension to '.mts' or create a local package.json file with `{ "type": "module" }`.

To Reproduce

https://codesandbox.io/s/i18next-fs-backend-issue-s4qlzc?file=/src/index.ts

Expected behavior

We should be able to import this library both from CJS context and ESM context.

Your Environment

• runtime version: node v18
• i18next version: ^22.4.9
• os: Mac

Solution 🔥

In order to solve the issue you have to provide two different types declaration files, for CJS and for ESM.

I played around a bit with the package.json configuration and found out that this one is actually working, allowing me to consume this library, not matter the context (CJS / ESM).

Although "./cjs/index.d.ts" and "./esm/index.js" is the same file.

{
  "type": "module",
  "main": "./cjs/index.js",
  "module": "./esm/index.js",
  "types": {
    "require": "./cjs/index.d.ts",
    "import": "./esm/index.d.ts"
  },
  "exports": {
    "./package.json": "./package.json",
    ".": {
      "types": {
        "require": "./cjs/index.d.ts",
        "import": "./esm/index.d.ts"
      },
      "require": "./cjs/index.js",
      "default": "./esm/index.js"
    },
    "./cjs": {
      "types": "./cjs/index.d.ts",
      "default": "./cjs/index.js"
    },
    "./esm": {
      "types": "./esm/index.d.ts",
      "default": "./esm/index.js"
    }
  },
}

Related topics 🔥

microsoft/TypeScript#49299
Swatinem/rollup-plugin-dts#210

The only one workaround for now

// @ts-ignore

😢

[adrai]

sorry, but this can't be the official way TypeScript wants us package maintainers to handle it...
//cc: @pedrodurek

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[e6c31d]

PR to fix this issue: #36

[adrai]

should be fixed with v2.1.2