Node.js error“ReferenceError: exports is not defined”

Why exports does not exist here, and the fix

1. 01

   A CommonJS file in a "type": "module" package

   “A package.json "type" value of "module" tells Node.js to interpret .js files within that package as using ES module syntax.” Node.js, Modules: Packages

   Adding "type": "module" to package.json turns every .js file into an ES module, including config files and scripts that still use exports or module.exports. Rename those to .cjs, or convert them to export.

   // before: config.js
   module.exports = { port: 3000 };
   
   // after: config.cjs (same code), or convert:
   export default { port: 3000 };

2. 02

   TypeScript compiled to CommonJS

   “You very likely want "nodenext" for modern Node.js projects and preserve or esnext for code that will be bundled.” TypeScript, TSConfig: module

   With "module": "commonjs", tsc writes exports.x = ... into every file. In a "type": "module" package, or in the browser, that output fails. Pick the module setting for where the code runs.

   // tsconfig.json for Node.js
   { "compilerOptions": { "module": "nodenext" } }
   
   // for code a bundler or the browser loads
   { "compilerOptions": { "module": "esnext" } }

3. 03

   CommonJS output loaded with a plain script tag

   A browser script has no exports object, so the first exports line throws. Serve ES modules with type="module", or run the code through a bundler such as Vite or esbuild that turns CommonJS into browser code.

   <script type="module" src="/js/app.js"></script>

4. 04

   Importing a CommonJS package from an ES module

   “In most cases, the ES module import can be used to load CommonJS modules.” Node.js, Modules: ECMAScript modules

   You do not need to rewrite a CommonJS dependency to use it from an ES module. Import it; Node.js maps module.exports to the default export.

   import pkg from 'some-commonjs-package';
   const { helper } = pkg;

Checked against the vendor’s docs on November 8, 2026: Node.js docs: Modules: Packages; Node.js docs: ECMAScript modules; TypeScript: TSConfig module.

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Related: “require is not defined” · “Cannot use import statement outside a module” · “Unexpected token 'export'”