Practical Techniques to Boost Angular Application Performance

Introduction:

Angular is a powerful framework for building powerful web applications, and optimization is key to providing a great user experience. In this post, we’ll go over some practical tips to improve Angular performance. Each tip is accompanied by code examples to illustrate the implementation.

1. Lazy Loading Modules: Lazy loading helps reduce the initial load time by loading modules on-demand. Use the **loadChildren** property in the route configuration to specify which modules should be lazily loaded.

const routes: Routes = [
 { path: 'lazy', loadChildren: () => import('./lazy/lazy.module').then(m => m.LazyModule) },
];

2. Ahead-of-Time (AOT) Compilation:

Enable AOT compilation to generate optimized and smaller bundles. AOT compilation reduces the bundle size and improves the application’s startup time.

3. Change Detection Strategy:

Optimize change detection by using OnPush strategy for components that don’t require frequent updates. This strategy reduces unnecessary checks and improves overall performance.

@Component({
 selector: 'app-example',
 templateUrl: './example.component.html',
 changeDetection: ChangeDetectionStrategy.OnPush,
})
export class ExampleComponent { }

4. TrackBy Function in ngFor:

When using ngFor directive, provide a trackBy function to track item changes efficiently. This reduces the re-rendering of elements that haven’t changed.

<ul>
 <li *ngFor="let item of items; trackBy: trackByFn">{{ item }}</li>
</ul>

Typescript

trackByFn(index: number, item: any): any {
 return item.id; // Replace with a unique identifier for each item
}

5. Unsubscribe when not in use:

Manually unsubscribe from subscriptions to prevent memory leaks. Use **takeUntil** operator and a subject to manage subscriptions and unsubscribe when the component is destroyed.

private destroy$ = new Subject();
ngOnInit(): void {
 someObservable$
 .pipe(takeUntil(this.destroy$))
 .subscribe((data) => {
 // Handle the data
 });
}
ngOnDestroy(): void {
 this.destroy$.next();
 this.destroy$.complete();
}

6. ChangeDetectionRef.markForCheck():

Use **markForCheck** () method from **ChangeDetectionRef** to selectively trigger change detection only when necessary. This can improve performance in specific scenarios.

constructor(private cdr: ChangeDetectorRef) { }
updateData(): void {
 // Update data here
 this.cdr.markForCheck();
}

7. NgZone Optimization:

Leverage the NgZone service to optimize the execution of code that doesn’t require Angular’s change detection. Use the **runOutsideAngular** method to execute code outside Angular’s zone.

constructor(private ngZone: NgZone) { }
performHeavyTask(): void {
 this.ngZone.runOutsideAngular(() => {
 // Perform heavy task here
 });
}

8. Avoid Excessive DOM Manipulation:

Minimize direct DOM manipulation and use Angular’s data binding and directives instead. Excessive DOM manipulation can impact performance negatively.

9. Use Angular Pipes Wisely:

Angular pipes can impact performance if used improperly. While pipes offer great flexibility and convenience, it’s important to use them judiciously to ensure optimal performance.

Angular provides two types of pipes: pure and impure. Pure pipes are memoized, meaning they only recalculate when the input value changes. This reduces unnecessary computations and improves performance. Always strive to use pure pipes whenever possible.

Avoid performing heavy computations within pipes, especially if the computation is not necessary for every change detection cycle. Complex calculations can introduce performance bottlenecks, so consider moving such computations to the component class or leveraging caching techniques to optimize performance.

@Pipe({
  name: 'instantPipe',
  pure: true
})
export class InstantPipe implements PipeTransform {
  transform(value: any): any {
    // Transformation logic here
  }
}

10. Debounce Input Events:

Use the debounceTime operator to reduce the frequency of input event handling. This prevents excessive updates and reduces unnecessary processing.

searchInput.valueChanges
 .pipe(debounceTime(300))
 .subscribe((value) => {
 // Handle the search value
 });

11. Optimize HTTP Requests:

Reduce the number of HTTP requests by combining multiple requests or using caching strategies. Leverage features like HTTP interceptors to handle common functionality across requests.

Example:

// Combine multiple HTTP requests
forkJoin([http.get('data1'), http.get('data2')]).subscribe(([data1, data2]) => {
  // Handle the responses
});

// Implement caching using an interceptor
@Injectable()
export class CachingInterceptor implements HttpInterceptor {
  // ...
}

12. Use Angular Reactive Forms:

Reactive Forms offer better performance than template-driven forms, especially when dealing with complex form scenarios. They provide more control and allow for fine-grained validation and data handling.

import { FormGroup, FormControl, Validators } from '@angular/forms';

const form = new FormGroup({
  name: new FormControl('', Validators.required),
  // ...
});

13. Angular Universal for Server-Side Rendering (SSR):

Implement Angular Universal for server-side rendering. SSR improves initial load times, enables search engine optimization, and provides a better user experience, especially for low-bandwidth or high-latency environments.

14. Use Angular Performance Tools:

Angular offers various performance tools, such as Angular DevTools and Augury , which provide insights into performance bottlenecks and help identify areas for optimization.

Conclusion :

By implementing these performance optimization tips, you can significantly enhance the speed and responsiveness of your Angular applications. Remember to analyze and profile your application to identify specific areas for improvement and measure the impact of these optimizations. Building performant Angular applications not only improves the user experience but also ensures scalability and efficiency.

Start incorporating these into your angular projects and experience the benefits firsthand. Happy coding!

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