how to subscribe to action success callback using ngrx and effects

You can subscribe to actions in components as well:

[...]
import { Actions } from '@ngrx/effects';
[...]

@Component(...)
class SomeComponent implements OnDestroy {
    destroyed$ = new Subject<boolean>();

    constructor(updates$: Actions) {
        updates$.pipe(
           ofType(PostActions.SAVE_POST_SUCCESS),
           takeUntil(this.destroyed$)
        )
        .subscribe(() => {
           /* hooray, success, show notification alert etc.. */
        });
    }

    ngOnDestroy() {
        this.destroyed$.next(true);
        this.destroyed$.complete();
    }
}