The index.js for Dog Saga - Redux-Saga Beginner Tutorial

index.js

import React from "react";
import ReactDOM from "react-dom";
import "./index.css";
import App from "./App";
import registerServiceWorker from "./registerServiceWorker";

import { createStore, applyMiddleware, compose } from "redux";
import createSagaMiddleware from "redux-saga";
import { Provider } from "react-redux";

import { reducer } from "./redux";
import { watcherSaga } from "./sagas";

// create the saga middleware
const sagaMiddleware = createSagaMiddleware();

// dev tools middleware
const reduxDevTools =
  window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__();

// create a redux store with our reducer above and middleware
let store = createStore(
  reducer,
  compose(applyMiddleware(sagaMiddleware), reduxDevTools)
);

// run the saga
sagaMiddleware.run(watcherSaga);

ReactDOM.render(
  <Provider store={store}>
    <App />
  </Provider>,
  document.getElementById("root")
);
registerServiceWorker();

According to official doc, Advanced store setup should be as followed:

import { createStore, applyMiddleware, compose } from "redux";

// redux dev-tool enhancer
const composeEnhancers = window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ || compose;

// redux store
let store = createStore(
  reducer,
  composeEnhancers(applyMiddleware(sagaMiddleware))
);