Package Exports

Packem treats your package.json#exports map as the source of truth for what your package ships. It reads the exports field to infer build entries, and it validates the field against the Node.js specification after building.

Entry inference from exports

During entry inference, Packem walks the exports map (via extractExportFilenames) and pairs each declared output path with a matching source file. Conditional keys such as import, require, and types, plus subpath patterns (e.g. "./*"), are all understood. A package.json like this:

{
  "exports": {
    ".": {
      "types": "./dist/index.d.ts",
      "import": "./dist/index.mjs",
      "require": "./dist/index.cjs"
    },
    "./utils": {
      "import": "./dist/utils.mjs",
      "require": "./dist/utils.cjs"
    }
  }
}

tells Packem to build two entries (index and utils) and to emit ESM, CJS, and declaration output for them.

Validating exports

After the build, Packem validates the exports field according to the Node.js packages specification (conditional exports, subpath exports, and the exports sugar form). You can toggle this through the validation options:

import { defineConfig } from '@visulima/packem/config'

export default defineConfig({
  validation: {
    packageJson: {
      exports: true, // set to false to skip exports validation
    },
  },
})

Related export options

Two adjacent options shape how entry inference and validation treat the exports map. Each has its own dedicated page:

• ignoreExportKeys — an array of export keys to skip during entry inference, useful for excluding keys that only point at images or other non-JavaScript assets, e.g. ["images", "assets", "icons"]. See Ignore Export Keys.
• validation.packageJson.allowedExportExtensions — extra file extensions to treat as valid inside the exports field during validation. See Allowed Export Extensions.

You can also widen the set of accepted conditional-export keys during validation with validation.packageJson.extraConditions (e.g. ["custom", "my-bundler"]).

Related Options

• Ignore Export Keys - Exclude keys from entry inference
• Allowed Export Extensions - Extra extensions for exports validation
• Declaration Files - .d.ts output referenced by types conditions
• Shims - ESM/CJS interop for the emitted entries