Injecting the Observable.ajax dependency in combineEpics before calling createEpicMiddleware

configureStore.js

import { createStore, applyMiddleware } from 'redux';
import { createEpicMiddleware, combineEpics } from 'redux-observable';
import { ajax } from 'rxjs/observable/dom/ajax';

import RootReducer from './reducers';
import saveFieldEpic from './epics/saveFieldEpic.js';


const rootEpic = (...args) => combineEpics(
    saveFieldEpic,
)(...args, {ajax});

const epicMiddleware = createEpicMiddleware(rootEpic);


export default function configureStore() {
    const store = createStore(
        RootReducer,
        applyMiddleware(epicMiddleware),
    );

    return store;
}