What is Redux? Understanding How Redux Works and Its Applications in React

In modern web development, React is one of the most popular JavaScript libraries for building user interfaces (UI). However, as applications grow in size and data becomes increasingly complex, managing application state can become a significant challenge. This is where Redux comes in—providing a centralized approach to state management that makes applications easier to control, maintain, and scale.

In this article, Viettel IDC explores what Redux is, how it works, and why it remains a widely used solution for state management in React applications.

What is Redux?

Redux is an open-source JavaScript library used for state management in web applications, particularly those with complex architectures and extensive data-sharing requirements.

Redux stores the entire application state in a centralized data store, ensuring that all components can access and update data consistently.

Instead of allowing individual components to manage their own isolated state—which can make data sharing difficult and error-prone—Redux provides a centralized architecture where all state changes are controlled, predictable, transparent, and easy to test.

Redux was created by Dan Abramov and Andrew Clark in 2015, inspired by Facebook’s Flux architecture. Today, Redux is considered one of the industry standards for state management in React applications and is also used with Angular, Vue, and even server-side Node.js applications.

Core Components of Redux

Redux architecture is built around three fundamental principles:

- A single source of truth

- State can only be modified through actions

- State updates are handled by pure functions called reducers

Store: The Centralized State Container

The Store is the heart of Redux, serving as the centralized repository that contains the entire state of an application.

Think of the store as a single data warehouse where all important application data is maintained.

Through the store, developers can access, update, and monitor state changes in a consistent manner. Each Redux application typically has only one store, ensuring data consistency and eliminating duplication across components.

Action: Describing What Happened

An Action is a plain JavaScript object that describes an event occurring within the application.

For example, when a user clicks an "Increase" button, the application may dispatch an action indicating that the value should be incremented by one.

An action generally contains:

- A type that identifies the action being performed (e.g., increment, decrement, update, delete)

- An optional payload containing additional data

Actions do not directly modify state. Instead, they simply notify the system that a particular event has occurred.

Reducer: Handling State Changes

A Reducer receives actions and determines how the application's state should change.

You can think of a reducer as the "brain" of Redux. When it receives an action such as "increment value by 1," it reads the current state, calculates the updated value, and returns a new state object.

One important rule is that reducers must never mutate the original state directly. Instead, they always return a new copy of the state, making changes predictable and easier to track.

How to Use Redux in React

After understanding the fundamentals of Redux, the next step is implementing it within a React application.

Below is a simplified overview of the Redux workflow in React.

Installing Redux and Related Libraries

To get started, developers typically install:

- Redux

- React-Redux

React-Redux acts as the bridge between React components and the Redux store, allowing UI components to access application state and dispatch actions based on user interactions.

The setup process is straightforward and prepares the application for centralized state management.

Creating the Store, Actions, and Reducers

Once the environment is ready, developers create:

- A store to hold application state

- Reducers to define state update logic

- Actions to describe user interactions and system events

For example, in a simple counter application:

- The reducer handles increment and decrement operations.

- Actions signal the desired operation.

- The store is initialized using the reducer.

The store is then shared throughout the React application using a Provider component, enabling child components to access state without excessive prop drilling.

Connecting React Components to the Redux Store

The final step is connecting React components to the Redux store.

Components can:

- Read data from the store

- Display state values in the UI

- Dispatch actions when users interact with buttons, forms, or other elements

Thanks to Redux's architecture, any state change automatically triggers UI updates, ensuring the application remains synchronized and responsive in real time.

Redux vs. Context API

Both Redux and the React Context API are used to share data between components, but they are designed for different use cases.

Context API

The Context API is built directly into React and works well for small to medium-sized applications where state management requirements are relatively simple.

However, as applications become larger and state logic grows more complex, Context API solutions can become difficult to maintain and may introduce performance challenges.

Redux

Redux is specifically designed for managing complex application state in large-scale applications.

It offers powerful tools and features such as:

- Middleware support

- Redux DevTools

- Redux Toolkit

- Advanced debugging capabilities

- Asynchronous state management

These features provide significantly greater control and scalability compared to Context API.

Benefits and Limitations of Redux

Benefits of Redux

Redux offers several advantages, especially for medium-to-large React applications.

Centralized State Management

By storing all application data in a single store, Redux makes it easier for components to access, share, and update information without passing props through multiple component levels.

Improved Debugging and State Tracking

Redux integrates with Redux DevTools, allowing developers to inspect every dispatched action and state change.

This significantly simplifies debugging and troubleshooting.

Predictable Data Flow

Redux uses a unidirectional data flow model, making applications more predictable, easier to maintain, and safer to scale.

The architecture also improves testability and long-term maintainability.

Limitations of Redux

Despite its advantages, Redux is not always the best solution.

Increased Complexity

For small applications, Redux may introduce unnecessary complexity and additional development overhead.

Developers often need to create multiple files for actions, reducers, and related configurations, resulting in more boilerplate code.

Steeper Learning Curve

Redux concepts such as action dispatching, reducers, middleware, and state architecture can be challenging for beginners.

Successfully implementing Redux requires a solid understanding of state management principles and application architecture.

As a result, Redux is generally more suitable for medium-sized and large-scale applications where centralized state management provides significant value.

When Should You Use Redux?

Use Redux When:

Redux is particularly beneficial if:

- Multiple components need to share and synchronize data.

- State update logic is complex and involves multiple dependencies.

- The project is large and maintained by multiple developers.

- Advanced debugging, state tracking, or time-travel debugging is required.

Common examples include:

- E-commerce platforms

- Administrative dashboards

- Social media applications

- Data analytics systems

- Enterprise web applications

Avoid Redux When:

Redux may be unnecessary if:

- The application is small.

- State management requirements are minimal.

- Data is rarely shared between components.

- Simpler solutions can meet project needs.

In these cases, alternatives such as:

- React Context + useReducer

- Zustand

- Jotai

may provide a more lightweight and efficient solution.

Conclusion

Redux is a powerful state management solution that helps React developers manage application data in a structured, consistent, and scalable way.

With its clear architecture and unidirectional data flow, Redux reduces bugs while making debugging, maintenance, and feature development significantly easier.

However, not every application requires Redux. The key is understanding your project's scale, complexity, and state management needs before selecting the right tool.

Even so, Redux remains a foundational technology and an essential part of many modern React applications, especially those that demand robust state management and long-term scalability.