Creating Angular Libraries (ng generate library)

Libraries allow sharing code between multiple applications or publishing to npm.

Generating a library

1. Create a new library in an existing workspace:

   ng generate library my-library

2. Generated structure:

   projects/
     my-library/
       src/
         lib/
           my-library.component.ts
           my-library.service.ts
           my-library.module.ts
         public-api.ts          # Public entry point
         ng-package.json         # Packaging configuration
         package.json            # Library dependencies
       ng-package.json
       package.json

Developing the library

• Export components/services in public-api.ts:

export * from "./lib/my-library.module";
export * from "./lib/my-library.service";
export * from "./lib/my-library.component";

• Configure ng-package.json to define the entry point and external dependencies.

Building and publishing

1. Build the library:

   ng build my-library

2. Navigate to the output folder:

   cd dist/my-library

3. Publish to npm (or use a local link):

   npm publish

Or create a local link for testing:

   npm link
   cd ../my-app
   npm link my-library

Using the library in an application

npm install my-library

Then import the module:

import { MyLibraryModule } from "my-library";

@NgModule({
  imports: [MyLibraryModule],
})
export class AppModule {}

Explanation:

• ng generate library creates a structure ready for packaging.

• The public-api.ts file controls what is exposed to consumers.
• Building produces a dist/ folder ready to publish.
• Use npm link to test locally before publishing.

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