Redux is a tool for state management commonly used in JavaScript applications, especially with React. It communicates the state of the entire application in a predictable and organized way for developers. Simply put, Redux is a “central store” for all the app data. When anything changes, it becomes easier to track and not become problematic due to a bug somewhere in the app. This centralized system helps with debugging, especially when the app grows larger, making Redux an essential tool for maintaining complex applications.

What is Redux?

Redux is a JavaScript library that aids in centralized application state management. In complex applications, managing multiple states can become difficult because the data may be scattered across various components. Redux solves this problem by storing all the application’s state in one central location known as the store.

Whenever something significant happens in the app, such as a user interaction or data returned from a server, Redux manages this event systematically through predefined functions. This makes the state changes predictable and easy to manage.

Key Concepts in Redux

Here are the key concepts to understand Redux:

  • Store: The store holds the entire application state in one place. Redux uses a global store to manage data centrally, which components access instead of keeping local state.
  • Actions: Actions are plain JavaScript objects that describe what event occurred. Every action contains a type field and, optionally, a payload with additional data.
  • Reducers: Reducers are functions that specify how the application’s state changes in response to an action. They take the current state and the action, and return the next state. Reducers must be pure functions, meaning they do not modify the current state directly but return a new state.
  • Dispatch: The dispatch function sends actions to the reducer, telling Redux to update the state based on the action.
  • Selectors: Selectors are functions used to extract specific data from the store, allowing components to access only the necessary state.

Example for Beginners

Let’s walk through a simple example to understand Redux better.

Step 1: Define Actions

what is redux in javascript ?
Here, we define two actions: INCREMENT and DECREMENT, each with a payload of 1, which modifies the state accordingly.

Step 2: Define a Reducer

const initialState = { count: 0 };

function counterReducer(state = initialState, action) {
  switch (action.type) {
    case 'INCREMENT':
      return { count: state.count + action.payload };
    case 'DECREMENT':
      return { count: state.count - action.payload };
    default:
      return state;
  }
}

The reducer function manages how the state changes in response to the INCREMENT and DECREMENT actions.

Step 3: Create the Store

import { createStore } from 'redux';

const store = createStore(counterReducer);

This step creates the Redux store, which holds the state. The store is now ready to manage and dispatch actions.

Step 4: Dispatch Actions

store.dispatch(incrementAction); // Increases count by 1
store.dispatch(decrementAction); // Decreases count by 1

Actions are dispatched using the dispatch function, which updates the state based on the action’s type.

Step 5: Access the State

console.log(store.getState()); // Outputs the current state

Once actions are dispatched, the updated state can be retrieved using the getState method.

How it Works?

The flow of Redux is simple:

  • A user performs an action in the app (like clicking a button).
  • This action is sent to the reducer, which updates the state based on the action.
  • The reducer processes the action and prepares the new state, storing it in the store.
  • The updated state is delivered to the components in the app, causing them to re-render if needed.

This flow ensures that data management in the app is predictable and easy to follow.

Benefits of Using Redux

  • Predictable: All changes to the app state happen through a well-defined process, making the data flow easier to understand and trace.
  • Single Source of Truth: Redux maintains the state in one store, preventing inconsistencies between components.
  • Easier Debugging: With a predictable flow of data, finding and fixing bugs becomes more straightforward.
  • Testable: Redux actions and reducers are pure functions, making them easy to test and enhancing the app’s reliability.

Real-World Usage

Redux is primarily used with React applications but can also be integrated with other JavaScript frameworks like Angular or Vue. Its main advantage in large applications is the ability to maintain consistent state across all components, especially when dealing with complex data structures or multi-page apps.

Conclusion

Redux offers a systematic and predictable approach to managing application state. By centralizing the state in a global store and allowing changes only through predefined actions, it helps developers create more maintainable, scalable, and easier-to-debug applications. Whether you are building a small project or a large-scale application, Redux simplifies state management, making it a popular choice in the modern JavaScript ecosystem, especially when working with React or other front-end frameworks.