How to watch object changes with rxjs 5

Question

I would like to watch over an object, so all the subscribers will be informed for any changes of it.

I saw it already been asked before, yet the answer is irrelevant si

Answer 1

I would suggest using something similar to redux approach, when changes to the object can be made in predefined way:

function factory(reducerByType, initialState) {
  const action$ = new Rx.Subject();
  const state$ = action$
    .startWith(initialState)
    .scan((state, action) => {
      if (reducerByType.hasOwnProperty(action.type)) {
        return reducerByType[action.type](state, action);
      }
      
      return state;
    })
    .distinctUntilChanged();
  
  
  return {
    action$,
    state$,
    dispatch: action => action$.next(action)
  }
}

const {state$, dispatch} = factory({
  ADD: (state, action) =>  state + action.number,
  SUBTRACT: (state, action) =>  state - action.number,
}, 0);

state$.subscribe(val => console.log(val));

dispatch({
  type: 'ADD',
  number: 10,
});

dispatch({
  type: 'SUBTRACT',
  number: 15,
});

dispatch({
  type: 'SUBTRACT',
  number: 0,
});