How to Use localStorage in Redux-Toolkit with NextJS: A Step-by-Step Guide

Are you tired of losing your application’s state when the user closes the browser or navigates away from your website? Do you want to provide a seamless user experience by persisting data even after the user returns to your site? Look no further! In this article, we’ll explore how to use localStorage in Redux-Toolkit with NextJS to achieve just that.

What is localStorage?

localStorage is a web storage mechanism that allows you to store data in the user’s browser. It’s a key-value storage system that allows you to store strings, and it’s accessible from JavaScript. Unlike cookies, localStorage is not sent with every HTTP request, making it a more efficient way to store data.

Why Use localStorage with Redux-Toolkit?

Redux-Toolkit is a popular state management library for React applications. When used with NextJS, it provides a robust way to manage your application’s state. However, by default, Redux-Toolkit does not persist data when the user closes the browser or navigates away from your website. That’s where localStorage comes in. By using localStorage with Redux-Toolkit, you can persist your application’s state even when the user returns to your site.

Setting Up the Project

To get started, create a new NextJS project using the following command:

npx create-next-app my-app

Next, install Redux-Toolkit and the required dependencies:

npm install @reduxjs/toolkit react-redux

Creating the Redux Store

Create a new file called `store.js` in the root of your project:

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

const store = configureStore({
  reducer: {
    // Add your reducers here
  }
});

export default store;

Creating a Reducer

Create a new file called `counterReducer.js`:

const initialState = {
  count: 0
};

const counterReducer = (state = initialState, action) => {
  switch (action.type) {
    case 'increment':
      return { count: state.count + 1 };
    case 'decrement':
      return { count: state.count - 1 };
    default:
      return state;
  }
};

export default counterReducer;

Adding the Reducer to the Store

Update the `store.js` file to add the `counterReducer`:

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

const store = configureStore({
  reducer: {
    counter: counterReducer
  }
});

export default store;

Using localStorage with Redux-Toolkit

To use localStorage with Redux-Toolkit, you’ll need to create a custom middleware. Create a new file called `localStorageMiddleware.js`:

import { applyMiddleware, combineReducers, createStore } from 'redux';
import { composeWithDevTools } from 'redux-devtools-extension';
import localStorage from 'localStorage';

const localStorageMiddleware = store => next => action => {
  const result = next(action);

  const state = store.getState();
  localStorage.setItem('reduxState', JSON.stringify(state));

  return result;
};

export default localStorageMiddleware;

Adding the Middleware to the Store

Update the `store.js` file to add the `localStorageMiddleware`:

import { configureStore } from '@reduxjs/toolkit';
import counterReducer from './counterReducer';
import localStorageMiddleware from './localStorageMiddleware';

const store = configureStore({
  reducer: {
    counter: counterReducer
  },
  middleware: [localStorageMiddleware]
});

export default store;

Hydrating the State from localStorage

To hydrate the state from localStorage, you’ll need to create a custom hydration function. Create a new file called `hydrateState.js`:

import localStorage from 'localStorage';

const hydrateState = () => {
  const storedState = localStorage.getItem('reduxState');
  if (storedState) {
    return JSON.parse(storedState);
  }
  return {};
};

export default hydrateState;

Updating the Store to Use the Hydration Function

Update the `store.js` file to use the `hydrateState` function:

import { configureStore } from '@reduxjs/toolkit';
import counterReducer from './counterReducer';
import localStorageMiddleware from './localStorageMiddleware';
import hydrateState from './hydrateState';

const initialState = hydrateState();

const store = configureStore({
  reducer: {
    counter: counterReducer
  },
  middleware: [localStorageMiddleware],
  initialState
});

export default store;

Using the Store in Your NextJS App

To use the store in your NextJS app, you’ll need to wrap your app with the `Provider` component from `react-redux`. Update your `pages/_app.js` file:

import React from 'react';
import { Provider } from 'react-redux';
import store from '../store';

function MyApp({ Component, pageProps }) {
  return (
    <Provider store={store}>
      <Component {...pageProps} />
    </Provider>
  );
}

export default MyApp;

Using the Store in Your Components

To use the store in your components, you’ll need to connect them to the store using the `connect` function from `react-redux`. Create a new file called `Counter.js`:

import React from 'react';
import { connect } from 'react-redux';

const Counter = ({ count, increment, decrement }) => {
  return (
    <div>
      <p>Count: {count}</p>
      <button onClick={increment}>Increment</button>
      <button onClick={decrement}>Decrement</button>
    </div>
  );
};

const mapStateToProps = state => {
  return { count: state.counter.count };
};

const mapDispatchToProps = dispatch => {
  return {
    increment: () => dispatch({ type: 'increment' }),
    decrement: () => dispatch({ type: 'decrement' })
  };
};

export default connect(mapStateToProps, mapDispatchToProps)(Counter);

Conclusion

In this article, we’ve explored how to use localStorage with Redux-Toolkit in a NextJS application. By persisting your application’s state to localStorage, you can provide a seamless user experience even after the user returns to your site. Remember to hydrate the state from localStorage when the user returns to your site, and to use the `Provider` component to wrap your app with the store.

Pros	Cons
Persisting state even after user closes browser	Requires additional setup and configuration
Provides seamless user experience	May not work with sensitive data
Easy to implement with Redux-Toolkit	May not work with certain browsers

Best Practices

• Use a custom middleware to persist the state to localStorage
• Hydrate the state from localStorage when the user returns to your site
• Use the `Provider` component to wrap your app with the store
• Avoid using localStorage with sensitive data
• Test your implementation with different browsers and scenarios

Common Issues

1. localStorage is not persisting data

   • Check that you’re using the correct syntax for setting and getting data from localStorage
   • Verify that the data is being serialized correctly

2. The state is not being hydrated correctly

   • Check that you’re calling the hydration function correctly
   • Verify that the state is being parsed correctly from localStorage

3. The store is not being updated correctly

   • Check that you’re using the correct syntax for updating the store
   • Verify that the store is being updated correctly in the reducer

By following the steps outlined in this article, you should be able to use localStorage with Redux-Toolkit in your NextJS application. Remember to test your implementation thoroughly and to follow best practices for storing and hydrating state.

Frequently Asked Questions

Get ready to unlock the power of localStorage in Redux-Toolkit with NextJS!