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ng-packagr

ng-packagr

Compile a TypeScript library to Angular Package Format

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Usage Example

For an Angular library, create one configuration file ng-package.json:

{
  "$schema": "./node_modules/ng-packagr/ng-package.schema.json",
  "lib": {
    "entryFile": "public_api.ts"
  }
}

Then, build the library from a npm/yarn script defined in package.json:

{
  "scripts": {
    "build": "ng-packagr -p ng-package.json"
  }
}

Now build with this command:

$ yarn build

Paths are resolved relative to the location of the ng-package.json file. The package.json describing the library should be located in the same folder, next to ng-package.json.

Features

Advanced Use Cases

Examples and Tutorials

Nikolas LeBlanc's story on medium.com: Building an Angular 4 Component Library with the Angular CLI and ng-packagr

Here is a demo repository showing ng-packagr and Angular CLI in action.

What about ng-packagr alongside Nx Workspace? Well, they work well together!

Configuration Locations

Configuration is picked up from the cli -p parameter, then from the default location for ng-package.json, then from package.json.

To configure with package.json, put your ng-package configuration in the ngPackage field:

{
  "$schema": "./node_modules/ng-packagr/package.schema.json",
  "ngPackage": {
    "lib": {
      "entryFile": "public_api.ts"
    }
  }
}

Note: the JSON $schema reference enables JSON editing support (autocompletion) for the custom ngPackage property in an IDE like VSCode.

Secondary Entry Points

Beside the primary entry point, a package can contain one or more secondary entry points (e.g. @angular/core/testing, @angular/cdk/a11y, …). These contain symbols that we don't want to group together with the symbols in the main entry. The module id of a secondary entry directs the module loader to a sub-directory by the secondary's name. For instance, @angular/core/testing resolves to a directory under node_modules/@angular/core/testing containing a package.json file that directs the loader to the correct location for what it's looking for.

For library developers, secondary entry points are dynamically discovered by searching for package.json files within sub directories of the main package.json file's folder!

So how do I use secondary entry points (sub-packages)?

All you have to do is create a package.json file and put it where you want a secondary entry point to be created. One way this can be done is by mimicking the folder structure of the following example which has a testing entry point in addition to its main entry point.

my_package
├── src
|   └── *.ts
├── public_api.ts
├── ng-package.json
├── package.json
├── testing
    ├── src
    |   └── *.ts
    ├── public_api.ts
    └── package.json

The contents of the secondary package.json can be as simple as:

{
  "ngPackage": {}
}

No, that is not a typo. No name is required. No version is required. It's all handled for you by ng-packagr! When built, the primary entry is imported with @my/library and the secondary entry with @my/library/testing.

What if I don't like public_api.ts?

You can change the entry point file by using the ngPackage configuration field in your secondary package.json. For example, the following would use index.ts as the secondary entry point:

{
  "ngPackage": {
    "lib": {
      "entryFile": "index.ts"
    }
  }
}
What if I want to use React Components?

If you have React Components that you're using in your library, and want to use proper JSX/TSX syntax in order to construct them, you can set the jsx flag for your library through ng-package like so:

{
  "$schema": "../../../src/ng-package.schema.json",
  "lib": {
    "entryFile": "public_api.ts",
    "externals": {
      "react": "React",
      "react-dom": "ReactDOM"
    },
    "jsx": "react"
  }
}

The jsx flag will accept anything that tsconfig accepts, more information here.

Note: Don't forget to include react and react-dom in your externals so that you're not bundling those dependencies.

Further documentation

We keep track of user questions in GitHub's issue tracker and try to build a documentation from it. Explore issues w/ label documentation.

Knowledge

Angular Package Format v4.0, design document at Google Docs

Packaging Angular - Jason Aden at ng-conf 2017 (28min talk): Packaging Angular - Jason Aden