Performance – Angular

Improving performance in an Angular 13 app involves a combination of best practices, optimizing code, and leveraging Angular-specific features. Here are some strategies to help improve the performance of your Angular app:

1. Lazy Loading Modules

• Use Lazy Loading: Load modules only when they are needed. This reduces the initial load time of the app.
  
  const routes: Routes = [ {
path: 'feature',
loadChildren: () => import('./feature/feature.module').then(m => m.FeatureModule)
} ];

2. OnPush Change Detection

• Change Detection Strategy: Use the OnPush change detection strategy to minimize the number of checks Angular performs.
  
  @Component({
selector: 'app-component',
templateUrl: './component.component.html',
changeDetection: ChangeDetectionStrategy.OnPush
})
export class Component {}

3. AOT Compilation

• Ahead-of-Time (AOT) Compilation: Ensure that your application is compiled ahead-of-time to reduce the size of the Angular framework and improve runtime performance.
  
  ng build --prod --aot

4. Optimize Template Rendering

• Avoid Unnecessary Bindings: Minimize the use of complex expressions in the templates.
  • TrackBy with ngFor: Use trackBy function to improve performance when rendering lists.
    
    <div *ngFor="let item of items; trackBy: trackByFn">
{{ item.name }}
</div>

trackByFn(index: number, item: any): number {
return item.id;
}

5. Service Workers and PWA

• Enable Service Workers: Use Angular’s service worker to cache assets and improve load times.
  
  ng add @angular/pwa

6. Minimize Bundle Size

• Tree Shaking: Ensure that unused code is not included in the production bundle.
  • Third-party Libraries: Import only necessary modules from third-party libraries.
    
    import { specificFunction } from 'large-library';

7. Use Angular CLI Build Optimizations

• Production Builds: Always use the Angular CLI with production flags for builds.
  
  ng build --prod

8. Avoid Memory Leaks

• Unsubscribe from Observables: Ensure that subscriptions are properly unsubscribed to avoid memory leaks.
  
  import { Subscription } from 'rxjs';
export class Component implements OnDestroy {
private subscription: Subscription = new Subscription();

ngOnInit() {
this.subscription.add(this.service.getData().subscribe());
}

ngOnDestroy() {
this.subscription.unsubscribe();
}
}

9. Optimize CSS and Assets

• Minimize CSS: Use tools like PurgeCSS to remove unused CSS.
• Optimize Images: Use modern image formats (e.g., WebP) and lazy load images.

10. Profiling and Performance Monitoring

• Angular DevTools: Use Angular DevTools to profile and monitor your application’s performance.
• Chrome DevTools: Use Chrome DevTools to identify performance bottlenecks.

11. Optimize Change Detection with Pipes

• Use Pure Pipes: Use Angular’s built-in or custom pure pipes to transform data in templates efficiently.

12. Server-Side Rendering (SSR)

• Angular Universal: Implement server-side rendering to improve the initial load time of your application.
  
  ng add @nguniversal/express-engine

13. Cache API Requests

• Http Interceptors: Implement caching for API requests using Angular’s HTTP interceptors.

14. Web Workers

• Offload Work: Use web workers to offload heavy computations to a background thread.

By implementing these strategies, you can significantly improve the performance of your Angular 13 application, providing a faster and smoother experience for your users.