ydn-fetching-data-effect-cancel.ts

@Effect getUsers$ = this.actions$.pipe(
  ofType('GET_USERS', 'CANCEL_GET_USERS'),
  withLatestFrom(this.userSelectors.needUsers$),
  filter(([action, needUsers]) => needUsers),
  map(([action, needUsers]) => action),
  switchMap(action => action.type === 'CANCEL_GET_USERS' ? 
    Observable.of() :
    this.getUsers().pipe(
      map(users => ({type: 'RECEIVE_USERS', users})),
    ),
  )
);