Handling Deprecation of combineReducers

Refactor existing code to handle the deprecation of `combineReducers` in favor of the new root reducer configuration.
// Assuming we're working with Redux toolkit

import { configureStore } from '@reduxjs/toolkit';

// Previously defined slice reducers
import userReducer from './features/userSlice';
import settingsReducer from './features/settingsSlice';

// Create a store with the new root reducer configuration
const store = configureStore({
  reducer: {
    user: userReducer,
    settings: settingsReducer

export default store;
In the updated code, we're using Redux Toolkit's `configureStore` method to create our store rather than the deprecated `combineReducers`. Each slice reducer is attached to a specific key within the new root reducer configuration.
<!DOCTYPE html>
<html lang="en">
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Redux Example</title>
  <div id="app"></div>
  <!-- Including the compiled JavaScript from bundler like Webpack -->
  <script src="path/to/bundled/javascript.js"></script>
This HTML file is where our React application will be rendered. It includes a script reference to the bundled JavaScript file, which will contain our refactored Redux configuration code.
body {
  margin: 0;
  padding: 0;
  font-family: 'Arial', sans-serif;

#app {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
This CSS snippet provides basic styling for the HTML page, setting a sans-serif font, 0 margin and padding for the body, and center alignment for the content in the `#app` div.