index.js

import React from "react";
import ReactDOM from "react-dom";
import { ConnectedRouter } from "connected-react-router";
import { Provider } from "react-redux";
import "redux-thunk";
import "@csstools/normalize.css";
import "reset-css";
import App from "./App";
import store from "./store";
import history from "./history";
import * as serviceWorker from "./serviceWorker";
ReactDOM.render(
  <Provider store={store}>
    <ConnectedRouter history={history}>
      <App />
    </ConnectedRouter>
  </Provider>,
  document.getElementById("root")
);
...
serviceWorker.unregister();