redux-with-rxjs.js

const createStore = (reducer, initialState) => {
  let dispatcher$ = new Rx.Subject();
  let state$ = new Rx.BehaviorSubject(initialState);

  dispatcher$.scan(reducer, state$.getValue()).subscribe(state$);

  return {
    dispatch(action) {
      dispatcher$.next(action);
    },
    subscribe(cb) {
      let sub = state$.subscribe(cb);
      return sub.unsubscribe.bind(sub);
    },
    getState() {
      return state$.getValue();
    }
  }
};


let reducer = (state = 0, action) => {
  if(action.type === 'INCREMENT') {
    return state + 1;
  }
  if(action.type === 'DECREMENT') {
    return state - 1;
  }
  return state;
};
let initialState = 0;

let store = createStore(reducer, initialState);

console.log(`state before sub ${store.getState()}`);

let unsub1 = store.subscribe(x => console.log(`sub1 ${x}`));
let unsub2 = store.subscribe(x => console.log(`sub2 ${x}`));

store.dispatch({ type: 'INCREMENT' });

unsub1();
unsub2();

console.log('unsub');

store.subscribe(x => console.log(`sub3 ${x}`));

store.dispatch({ type: 'INCREMENT' });