CJS Default Export

The cjsDefault option helps improve compatibility when generating CommonJS (CJS) modules. This option is enabled by default.

How It Works

When your module has only a single default export and the output format is set to CJS, tsdown will automatically transform:

• export default ... into module.exports = ... in the generated JavaScript file.

For TypeScript declaration files (.d.ts), it will transform:

• export default ... into export = ...

This ensures that consumers using CommonJS require syntax (require('your-module')) will receive the default export directly, improving interoperability with tools and environments that expect this behavior.

Example

Source Module:

// src/index.ts
export default function greet() {
  console.log('Hello, world!')
}

Generated CJS Output:

// dist/index.cjs
function greet() {
  console.log('Hello, world!')
}
module.exports = greet

Generated Declaration File:

// dist/index.d.cts
declare function greet(): void
export = greet