nx/docs/shared/recipes/tips-n-tricks/define-secondary-entrypoints.md

Define Secondary Entry Points for Typescript Packages

If you have a package where you want people to be able to access more than just the main file, you can define an exports property in the package.json file. Like this:

{
  "exports": {
    "./package.json": "./package.json",
    ".": "./src/index.js",
    "./foo": "./src/foo.js",
    "./bar": "./src/bar.js"
  }
}

Then people can access code in your library through any of the provided entry points.

import myLib from 'my-lib';
import foo from 'my-lib/foo';
import bar from 'my-lib/bar';

Setup package.json export fields with Nx

Nx helps generate other properties in the package.json file, and you can also use Nx to maintain this property.

If you're using the @nx/js:tsc executor, as of Nx 16.8, you can specify the additionalEntryPoints and generateExportsField options. Here's an example:

{% tabs %} {%tab label="package.json"%}

{
  "name": "my-awesome-lib",
  "nx": {
    "targets": {
      "build": {
        "executor": "@nx/js:tsc",
        "options": {
          "main": "packages/my-awesome-lib/src/index.ts",
          "additionalEntryPoints": [
            "packages/my-awesome-lib/src/foo.ts",
            "packages/my-awesome-lib/src/bar.ts"
          ],
          "generateExportsField": true
        }
      }
    }
  }
}

{% /tab%} {%tab label="project.json"%}

{
  "name": "my-awesome-lib",
  "targets": {
    "build": {
      "executor": "@nx/js:tsc",
      "options": {
        "main": "packages/my-awesome-lib/src/index.ts",
        "additionalEntryPoints": [
          "packages/my-awesome-lib/src/foo.ts",
          "packages/my-awesome-lib/src/bar.ts"
        ],
        "generateExportsField": true
      }
    }
  }
}

{% /tab%} {% /tabs %}

When building the library, the @nx/js:tsc executor automatically adds the correct exports definition to the resulting package.json.

Compile to Multiple Formats

You can also compile to multiple formats, if you switch to using the @nx/rollup:rollup executor. Read all the details here.