What is Redux Thunk? Why we need it?

Redux is a popular state management library used in many web and mobile applications. It's a predictable state container for JavaScript apps that helps in managing the state of the application. However, when it comes to handling asynchronous actions like API calls or handling side effects, Redux alone is not enough. This is where Redux Thunk comes into play.

Redux Thunk is a middleware for Redux that allows you to write asynchronous logic that interacts with the Redux store. In this article, we will explore what Redux Thunk is, why we need it, and how to use it in a Redux application.

What is Redux Thunk?

Redux Thunk is a middleware that allows you to write asynchronous logic that interacts with the Redux store. It enables you to write action creators that return a function instead of an action object. This function can then dispatch actions and perform asynchronous operations before dispatching the actual action.

Why do we need Redux Thunk?

Redux follows a strict pattern of "dispatching an action that triggers a state change." However, this pattern is not enough when it comes to handling asynchronous operations. Let's consider an example where we need to fetch some data from an API before dispatching an action to update the state.

Without Redux Thunk, we would have to write a separate action creator for each step of the process. One action creator to initiate the API request, another to handle the response, and yet another to dispatch the actual action. This can become messy and difficult to manage, especially when dealing with complex operations.

Redux Thunk simplifies this process by allowing us to write a single action creator that can perform multiple tasks asynchronously before dispatching the actual action.

How to use Redux Thunk in a Redux application?

To use Redux Thunk in your Redux application, you first need to install the redux-thunk middleware using npm or yarn:

npm install redux-thunk

or

csharp
yarn add redux-thunk

Next, you need to apply the middleware to your Redux store using the applyMiddleware function from the redux package:

javascript
import { createStore, applyMiddleware } from 'redux';
 import thunk from 'redux-thunk'; 
import rootReducer from './reducers'; 
 const store = createStore(rootReducer, applyMiddleware(thunk));

In this example, we import the createStore and applyMiddleware functions from the redux package, as well as the thunk middleware from redux-thunk. We then apply the middleware to our store using the applyMiddleware function.

Now that we have added the redux-thunk middleware to our store, we can write action creators that return a function instead of an action object. Let's consider an example where we need to fetch some data from an API before dispatching an action to update the state.

javascript
export const fetchUserData = (userId) => {
   
return (dispatch) => {
     
dispatch({ type: 'FETCH_USER_DATA_REQUEST' }); 
fetch(`https://jsonplaceholder.typicode.com/users/${userId}`)
      .then((response) => response.json())
      .then((data) => {
         
dispatch({ type: 'FETCH_USER_DATA_SUCCESS', payload: data });
      })
      .catch((error) => {
         
dispatch({ type: 'FETCH_USER_DATA_FAILURE', payload: error });
      });
  };
};

In this example, we define an action creator called fetchUserData that takes a userId parameter. This action creator returns a function that takes a dispatch parameter.

Inside the function, we dispatch an action to indicate that we are initiating the API request. We then use the fetch function to make the API request and handle the response in a promise chain.

If the request is successful, we dispatch another action