// actions.ts
const STORAGE = '@ngrx/store/storage';

export class Storage implements Action {
  readonly type = STORAGE;
  constructor(readonly payload: string) {}
}

// reducers.ts
import { localStorageSync, rehydrateApplicationState } from 'ngrx-store-localstorage';

export function localStorageSyncReducer(reducer: ActionReducer<any>): ActionReducer<any> {
  return (state: State, action: All) => {
    const keys = ['key1', 'key2'];

    if  (action.type === STORAGE && keys.includes(action.payload)) {
      const rehydratedState = rehydrateApplicationState([action.payload], localStorage, k => k);
      return { ...state, ...rehydratedState };
    }

    return localStorageSync({
      keys,
      rehydrate: true,
    })(reducer)(state, action);
  }
}

// app.component.ts
export class AppComponent implements OnInit {
  constructor(
    private readonly renderer: Renderer2,
    private readonly store: Store<State>,
  ) {}

  ngOnInit() {
    this.renderer.listen('window', 'storage', event => {
      this.store.dispatch(new Storage(event.key));
    });
  }
}