How to use react-redux library to manage state in react application

React-Redux is the official binding library for integrating React with Redux. It provides hooks and higher-order components that allow your React components to interact with the Redux store. React-Redux simplifies the process of connecting components to the Redux store and helps manage state in a predictable way.

Key Concepts

1. Provider: A component that makes the Redux store available to any nested components that need to access the Redux store.
2. useSelector: A hook that allows you to extract data from the Redux store state.
3. useDispatch: A hook that allows you to dispatch actions to the Redux store.

Example

Let's walk through a simple example of using React-Redux to manage a counter application's state.

Setting Up Redux

1. Install Dependencies:

npm install @reduxjs/toolkit react-redux

2. Create a Redux Slice:

Create a slice to manage the counter state.

// counterSlice.js
import { createSlice } from '@reduxjs/toolkit';

const counterSlice = createSlice({
  name: 'counter',
  initialState: { value: 0 },
  reducers: {
    increment: (state) => {
      state.value += 1;
    },
    decrement: (state) => {
      state.value -= 1;
    },
    incrementByAmount: (state, action) => {
      state.value += action.payload;
    }
  }
});

export const { increment, decrement, incrementByAmount } = counterSlice.actions;
export default counterSlice.reducer;

3. Configure the Store:

Combine the slice reducer into the Redux store.

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

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

export default store;

Setting Up React-Redux

1. Provide the Store to Your App:

Wrap your application with the Provider component to give access to the Redux store.

// index.js
import React from 'react';
import ReactDOM from 'react-dom';
import { Provider } from 'react-redux';
import App from './App';
import store from './store';

ReactDOM.render(
  <Provider store={store}>
    <App />
  </Provider>,
  document.getElementById('root')
);

2. Connect Components to the Redux Store:

Use useSelector to access state and useDispatch to dispatch actions.

// App.js
import React from 'react';
import { useSelector, useDispatch } from 'react-redux';
import { increment, decrement, incrementByAmount } from './counterSlice';

const App = () => {
  const count = useSelector((state) => state.counter.value);
  const dispatch = useDispatch();

  return (
    <div className="flex flex-col items-center justify-center h-screen bg-gray-100">
      <h1 className="text-2xl mb-4">Counter: {count}</h1>
      <div className="flex space-x-2">
        <button
          className="bg-blue-500 text-white px-4 py-2 rounded"
          onClick={() => dispatch(increment())}
        >
          Increment
        </button>
        <button
          className="bg-red-500 text-white px-4 py-2 rounded"
          onClick={() => dispatch(decrement())}
        >
          Decrement
        </button>
        <button
          className="bg-green-500 text-white px-4 py-2 rounded"
          onClick={() => dispatch(incrementByAmount(5))}
        >
          Increment by 5
        </button>
      </div>
    </div>
  );
};

export default App;

Explanation

1. Provider:

   • The Provider component wraps the App component and makes the Redux store available to all components in the app.

2. useSelector:

   • The useSelector hook is used to access the current state of the counter from the Redux store. It subscribes to the store and re-renders the component whenever the selected state changes.

3. useDispatch:

   • The useDispatch hook is used to dispatch actions to the Redux store. In this example, it's used to dispatch increment, decrement, and incrementByAmount actions.

4. Actions and Reducers:

   • The increment, decrement, and incrementByAmount actions are defined in the counterSlice and used to update the state in response to user interactions.

Benefits of Using React-Redux

1. Separation of Concerns:

   • Keeps UI logic and state management logic separate, making the application easier to manage and scale.

2. Predictable State Management:

   • State transitions are predictable and managed through a single source of truth (the Redux store).

3. Ease of Testing:

   • Components can be easily tested in isolation because state management logic is separated.

4. Performance Optimization:

   • React-Redux uses shallow equality checking to prevent unnecessary re-renders, optimizing performance.