simplified ngrx

simplified_ngrx.js

class Dispatcher extends Rx.Subject{
  dispatch(value : any) : void {
    this.next(value);
  }
}

class Store extends Rx.BehaviorSubject{
  constructor(
    private dispatcher,
    private reducer,
    preMiddleware,
    postMiddleware,
    initialState = {}
  ){
    super(initialState);
    this.dispatcher 
       .let(preMiddleware)
       .scan((state, action) => this.reducer(state, action), initialState)
       .let(postMiddleware) 
       .subscribe(state => super.next(state));
  }
  
  /*
    distinctUntilChanged only emits new values when output is distinct, per last emitted value. 
    In the example below, the observable with the distinctUntilChanged operator will emit one less value then the other       with only the map operator applied
  */
  select(key : string) {
    return this
      .map(state => state[key])
      .distinctUntilChanged();
  }

  //...store implementation
  
  const subscriber = store
  //with distinctUntilChanged
  .select('person')
  .subscribe(val => console.log('PERSON WITH DISTINCTUNTILCHANGED:', val));
const subscriberTwo = store
  //without distinctUntilChanged, will print out extra time
  .map(state => state.person)
  .subscribe(val => console.log('PERSON WITHOUT DISTINCTUNTILCHANGED:', val));
//dispatch a few actions
dispatcher.dispatch({
  type: 'ADD_INFO', 
  payload: {
    name: 'Brian', 
    message: 'Exploring Reduce!'
  }
});
//person will not be changed
dispatcher.dispatch({
  type: 'ADD_HOUR'
});
}