Change Detection Strategy onpush in Angular
- https://alligator.io/angular/change-detection-strategy/
- https://stackblitz.com/edit/change-detection-strategy1
- https://blog.ninja-squad.com/2018/09/27/angular-performances-part-4/
- https://netbasal.com/a-comprehensive-guide-to-angular-onpush-change-detection-strategy-5bac493074a4 (VVI, ************, please study more)
Change Detection Strategy onpush follow some rules: You may need to take care this rules
Rule 1: @Inputs: Input properties value will be changed when its ref will be changed
Rule 2: A component have own internal state. in the ts file , if value change due to api or set-timeout it will not show in html page directly. it only show when any event(click, change) occur from the html page.
Rule 3: We run change detection explicitly. The first is detectChanges() which tells Angular to run change detection on the component and his children.
onstructor(private cdr: ChangeDetectorRef) {
setTimeout(() => {
this.count = 5; this.cdr.detectChanges();
}, 1000);
}
Rule 4: Angular Async Pipe. The async pipe subscribes to an observable or promise and returns the latest value it has emitted
see the example of above link
If a component depends only on its input properties, and they are observable, then this component can change if and only if one of its input properties emits an event.
Rule 5: onPush and View Queries.
@Input() set content(value) {
this._content = value;
this.cdr.markForCheck();
}
Rule 6: === onPush++ (VVVVIIIIII)
Also, by creating a dedicated component we make our code more readable and reusable.
See the example of above medium doc link
https://netbasal.com/a-comprehensive-guide-to-angular-onpush-change-detection-strategy-5bac493074a4
Rule 3: We run change detection explicitly. The first is detectChanges() which tells Angular to run change detection on the component and his children.
onstructor(private cdr: ChangeDetectorRef) {
setTimeout(() => {
this.count = 5; this.cdr.detectChanges();
}, 1000);
}
Rule 4: Angular Async Pipe. The async pipe subscribes to an observable or promise and returns the latest value it has emitted
see the example of above link
If a component depends only on its input properties, and they are observable, then this component can change if and only if one of its input properties emits an event.
Rule 5: onPush and View Queries.
@Input() set content(value) {
this._content = value;
this.cdr.markForCheck();
}
Rule 6: === onPush++ (VVVVIIIIII)
Also, by creating a dedicated component we make our code more readable and reusable.
See the example of above medium doc link
https://netbasal.com/a-comprehensive-guide-to-angular-onpush-change-detection-strategy-5bac493074a4
