Mastering NX Libraries: Building Reusable Code in Your Angular Monorepo

Types of NX Libraries: Building Blocks of Your Application

Feature Libraries

Feature libraries contain smart components and business logic for specific application features.

nx g @nx/angular:lib orders --directory=features        

Example structure:

libs/features/orders/
├── src/
│   ├── lib/
│   │   ├── orders-list/
│   │   ├── order-detail/
│   │   └── orders.service.ts
│   └── index.ts
└── project.json        

UI Libraries

Contains dumb/presentational components shared across applications.

nx g @nx/angular:lib ui --directory=shared        

Example component:

// libs/shared/ui/src/lib/button/button.component.ts
@Component({
  selector: 'shared-button',
  template: `
    <button [class]="variant" [disabled]="disabled">
      <ng-content></ng-content>
    </button>
  `,
  standalone: true
})
export class ButtonComponent {
  @Input() variant: 'primary' | 'secondary' = 'primary';
  @Input() disabled = false;
}        

Utility Libraries

Houses shared functions, pipes, and services.

nx g @nx/angular:lib utils --directory=shared        

Example utility:

// libs/shared/utils/src/lib/date/format-date.ts
export function formatDate(date: Date): string {
  return new Intl.DateTimeFormat('en-US', {
    year: 'numeric',
    month: 'long',
    day: 'numeric'
  }).format(date);
}        

Best Practices for Library Organization

1. Clear Boundaries

libs/
├── shared/          # Shared across all apps
│   ├── ui/
│   └── utils/
├── features/        # Business features
│   ├── orders/
│   └── products/
└── data-access/     # API interfaces        

2. Dependency Rules

• Feature libraries can depend on UI and utility libraries
• UI libraries should not depend on feature libraries
• Avoid circular dependencies

3. Library Tags

// nx.json
{
  "projects": {
    "shared-ui": {
      "tags": ["type:ui", "scope:shared"]
    },
    "feature-orders": {
      "tags": ["type:feature", "scope:orders"]
    }
  }
}        

4. Export Strategy

// libs/shared/ui/src/index.ts
export * from './lib/button/button.component';
export * from './lib/card/card.component';        

Real-World Implementation

Creating a feature library with associated components:

# Create feature library
nx g @nx/angular:lib orders --directory=features

# Add components
nx g @nx/angular:component order-list --project=features-orders
nx g @nx/angular:component order-detail --project=features-orders

# Add service
nx g @nx/angular:service orders --project=features-orders        

Performance Tips

1. Use Standalone Components

@Component({
  selector: 'app-feature',
  standalone: true,
  imports: [CommonModule, SharedUiModule]
})        

2. Implement Lazy Loading

const routes: Routes = [{
  path: 'orders',
  loadChildren: () => import('@myorg/features/orders')
}];        

3. Enable Computation Caching

// nx.json
{
  "tasksRunnerOptions": {
    "default": {
      "runner": "nx/tasks-runners/default",
      "options": {
        "cacheableOperations": ["build", "test"]
      }
    }
  }
}        

#Angular #NX #WebDevelopment #Frontend #JavaScript #TypeScript #Monorepo #CleanArchitecture #SoftwareEngineering #DeveloperTools