CommonJS consumers get "exports is not defined"

[ArCheeq]

---

Describe the bug

When the package is required from a CommonJS application (e.g. NestJS, or any Node app that uses require() or compiles to CommonJS), Node throws:

ReferenceError: exports is not defined in ES module scope
This file is being treated as an ES module because it has a '.js' file extension and '.../node_modules/fish-audio/package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.
    at file:///.../node_modules/fish-audio/dist/cjs/index.js:16:23

So the CJS build (dist/cjs/index.js) is being executed as an ES module, and its CommonJS-style exports usage is invalid in ESM scope.

Root cause

• In package.json you have "type": "module", so Node treats all .js files in the package as ES modules.
• The exports field maps "require" to ./dist/cjs/index.js.
• When a CJS app does require('fish-audio'), Node loads that file. Because of "type": "module", that .js file is interpreted as ESM, not CommonJS. The file content is CommonJS (exports.FishAudioClient = ..., etc.), so you get ReferenceError: exports is not defined.

So the CJS entry is shipped as .js inside a package that is fully ESM — that combination is invalid for CJS consumers.

Environment

• Package version: 0.1.0 (and any version with the same package.json + CJS build layout).
• Node: 18+ (tested on current LTS).
• Consumer: Any project that uses CommonJS (e.g. TypeScript with "module": "commonjs", or plain Node with require()).

Expected behavior

• CJS consumers: require('fish-audio') should load the CJS build and run without errors.
• ESM consumers: import 'fish-audio' / import('fish-audio') should continue to load the ESM build.

Suggested fix

Keep "type": "module" for the ESM build, but make the CJS build explicitly CommonJS so Node does not treat it as ESM:

1. Output the CJS build with the .cjs extension (e.g. dist/cjs/index.cjs), so Node always runs it as CommonJS regardless of "type": "module". Internal require() calls within the CJS build must reference the same .cjs files, or the build tool must emit/rename them accordingly.
2. Point the require condition in package.json to that file:

"exports": {
  ".": {
    "require": "./dist/cjs/index.cjs",
    "import": "./dist/esm/index.js"
  }
}

Reference: Node.js — Determining module system: in a package with "type": "module", .js is treated as ESM; .cjs is always CommonJS.