private _nationalProps: BehaviorSubject<NationalProp[]> = new BehaviorSubject<NationalProp[]>([]);

get national() {
    return this._nationalProps.pipe(take(1), map(nprops => {
      return [...nprops];
    })
    );

deleteNationalProp(id: string) {
    return this.http.delete(this.serverUrl + `/national_props/${id}.json`)
          .pipe(
          switchMap(() => {
            return this._nationalProps;
          }),
          take(1),
          tap(props => {
      this._nationalProps.next(props.filter(b => b.id !== id));
    }));
  }

propSub: Subscription; // imported from rxjs
loadedProps: NationalProp[];

ngOnInit() {
 this.propSub = this.servicesSrv.national.subscribe(props => {
      this.loadedProps = props;
    });

this.servicesSrv.deleteNationalProp(pId).subscribe();

get national() {
    return this._nationalProps.pipe(map(nprops => {
      return [...nprops];
    })
    );
}