scinote-web/app/javascript/src/config/store.js

import { createStore, applyMiddleware, compose } from "redux";
import thunk from "redux-thunk";
import rootReducer from "./reducers";

const store = createStore(
  rootReducer,
  compose(
    applyMiddleware(thunk),
    typeof window === "object" &&
    typeof window.devToolsExtension !== "undefined"
      ? window.devToolsExtension()
      : f => f
  )
);

export default store;