Fix TypeScript Declarations for default CJS exports

This utility will allow you to fix the TypeScript declaration in CommonJS modules when using default exports.

Check the CJS fixtures in the test folder and the CJS document for further details when using rollup-plugin-dts.

Features

• 🚀 Fix default exports in CommonJS modules via API or Rollup plugin
• ✨ Generate CommonJS d.ts and d.cts files from d.mts files
• 💥 Use it with custom builders like unbuild, tsup or pkgroll (right now only unbuild supported, tsup and pkgroll don't allow adding Rollup plugins)

unbuild

Note

unbuild v3.5.0 uses the Rollup plugin from this package to fix the default exports in CommonJS modules.

For older unbuild versions, you can add the Rollup plugin from this package using the rollup:dts:options hook.

Warning

You should register the plugin directly when enabling rollup.emitCJS = true option, otherwise you can get wrong transformations.

The plugin exposed here is just a helper to fix the default exports in CommonJS modules, it cannot control what files are being generated, check the declaration option in the readme file.

You will need to remove its current internal plugin adding the one provided by this package:

// build.config.ts
import { FixDtsDefaultCjsExportsPlugin } from 'fix-dts-default-cjs-exports/rollup'
import { defineBuildConfig } from 'unbuild'

export default defineBuildConfig({
  entries: ['<your-entry-points>'],
  declaration: true,
  clean: true,
  rollup: { emitCJS: true },
  hooks: {
    'rollup:dts:options': (ctx, options) => {
      /* uncomment this block if you want to remove the unbuild internal plugin
      options.plugins = plugins.filter((p) => {
        if (!p || typeof p === 'string' || Array.isArray(p) || !('name' in p))
          return true

        return p.name !== 'unbuild-fix-cjs-export-type'
      })
      */
      options.plugins.push(FixDtsDefaultCjsExportsPlugin({
        warn: message => ctx.warnings.add(message)
      }))
    }
  }
})

tsup

Since tsup doesn't expose any hook to allow change internal configuration, we need a change in the package to include the Rollup plugin from this package instead its built-in one.

pkgroll

pkgroll is exposing only the cli, we need a change in the package to include the Rollup plugin from this package instead its built-in one.

License

MIT License © 2025-PRESENT Joaquín Sánchez