One of the key features of many applications is the ability to undo and redo certain actions. This functionality can be particularly useful in scenarios where users may make mistakes or wish to revert back to a previous state. In this blog post, we will explore how to implement undo and redo functionality using Redux Toolkit, a powerful toolset for managing state in React applications.

Prerequisites

To follow along with this tutorial, you should have a basic understanding of Redux Toolkit and React.

Getting Started

Before diving into the implementation details, let’s install Redux Toolkit and set up a basic Redux store in our React application. Open your terminal and run the following command to install Redux Toolkit:

npm install @reduxjs/toolkit

Next, create a new file named store.js and add the following code to set up a basic Redux store:

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

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

export default store;

Implementing State History

To enable undo and redo functionality, we need to maintain a history of state changes. Redux Toolkit provides a createSlice function that simplifies the process of creating reducers. We can extend this functionality to keep track of state history.

Modify your store.js file as follows:

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

const stateHistorySlice = createSlice({
  name: 'stateHistory',
  initialState: [],
  reducers: {
    saveState: (state, action) => {
      state.push(action.payload);
    },
  },
});

const { saveState } = stateHistorySlice.actions;

export const { reducer: stateHistoryReducer } = stateHistorySlice;

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

export const store.dispatch(saveState({ /* initial state */ }));

export default store;

In the above code, we define a stateHistory slice using createSlice. This slice holds an array of previous states. We also add a saveState reducer that takes the current state and adds it to the history array.

Lastly, we dispatch an initial saveState action with the initial state of your application. This ensures that the initial snapshot is stored in the history.

Implementing Undo and Redo

Now that we have set up the state history, we can proceed to implement the undo and redo functionality in our components.

Add the following code to your component file:

import React from 'react';
import { useSelector, useDispatch } from 'react-redux';
import { saveState } from './store';

function MyApp() {
  const stateHistory = useSelector((state) => state.stateHistory);
  const currentStateIndex = stateHistory.length - 1;
  const currentState = stateHistory[currentStateIndex];
  
  const dispatch = useDispatch();
  
  const handleUndo = () => {
    // Perform undo logic here
  };
  
  const handleRedo = () => {
    // Perform redo logic here
  };

  return (
    <div>
      {/* Your application UI */}
      <button onClick={handleUndo} disabled={currentStateIndex === 0}>Undo</button>
      <button onClick={handleRedo} disabled={currentStateIndex === stateHistory.length - 1}>Redo</button>
    </div>
  );
}

export default MyApp;

In the above code snippet, we use the useSelector hook to get access to the stateHistory array from our Redux store. We calculate the current state index and the current state based on the length of the stateHistory array.

We also use the useDispatch hook to get the Redux dispatch function. This allows us to dispatch actions to update the state or trigger undo and redo functionality.

The handleUndo and handleRedo functions perform the logic for undo and redo. You can customize these functions based on the requirements of your application.

Conclusion

By utilizing Redux Toolkit and a state history, we have successfully implemented undo and redo functionality in our React application. Users can now revert back to previous states or redo actions they have undone. Implementing undo and redo functionality can greatly enhance the user experience of your application.