Understanding Angular 16 Signals with OnPush Change Detection

Angular 16 introduces a new feature called signals, which allows for more efficient change detection using the OnPush strategy.

What are Signals?

Signals in Angular 16 are a way of marking components to be checked for changes even when using the OnPush change detection strategy. This allows for better performance and more predictable behavior in complex applications.

Using Signals with OnPush Change Detection

When using OnPush change detection in Angular 16, components can be marked with a signal to indicate that they should be checked for changes, even if their inputs have not changed. This can be done using the @Signal decorator.

  @Component({
    selector: 'app-example',
    changeDetection: ChangeDetectionStrategy.OnPush
  })
  export class ExampleComponent {
    @Input() data: any;
    
    @Signal() checkForChanges: boolean;
  }
  

In the above example, the ExampleComponent is using the OnPush change detection strategy, but it also has a checkForChanges signal that will trigger change detection, even if the data input has not changed.

Benefits of Using Signals

Using signals with OnPush change detection can lead to better performance and more predictable behavior in Angular applications. By explicitly marking components to be checked for changes, developers can avoid unnecessary change detection cycles and improve the overall performance of their applications.

Conclusion

Angular 16 signals provide a powerful way to improve change detection performance in applications using the OnPush strategy. By using signals, developers can have more control over when change detection occurs, leading to better performance and a more predictable user experience.