Best practice when using an observable...

subject-takeuntill.ts

     this.titleService.emitterN$
            .takeUntil(this.componentDestroyed$)
            .subscribe(
            (data: any) =>
            {
                // ... do something N
            }
        );
    }

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