Simple ngrx effect example with `withLatestFrom` operator for blog post: https://medium.com/@viestursv/how-to-get-store-state-in-ngrx-effect-fab9e9c8f087#.oekqp1ucb

line.effect.ts

import { Store, Action } from '@ngrx/store';
import { Actions, Effect } from '@ngrx/effects';

import 'rxjs/add/operator/map';
import 'rxjs/add/operator/filter';
import 'rxjs/add/operator/withLatestFrom';

import { ADD_LINE } from './lines.reducer';
import { INC_PAGE_COUNT } from './pages.reducer';
import { AppState } from './app.store';


@Injectable()
export class LineEffects {

  @Effect() increasePageCount$ = this.actions$
    .ofType(ADD_LINE)
    .withLatestFrom(this.store$)
    .filter(([action: Action, storeState: AppState]) => {
      return storeState.lines.length / 100 > storeState.pages.count;
    })
    .map((actionAndStoreState) => {
      return {
        type: INC_PAGE_COUNT
      }
    });

  constructor (
    private actions$: Actions,
    private store$: Store<AppState>) {
  }
}