Please note that PubNub will discontinue support for Chat Components on January 1, 2025. They will remain open-source and community-maintained but will no longer receive feature updates from PubNub.
Read here how to migrate Chat Components to Chat SDK
What is React?
React is a powerful JavaScript library for building UIs, known for its declarative, efficient, and component-based approach. It manages state and rendering at the component level, but complex applications often require additional libraries for full functionality.
While a web app can be built solely with React, integrating backend tools is essential for real-time features. PubNub enhances React apps by providing scalable, real-time state management, enabling seamless in-app chat, virtual spaces, and live updates. With React’s popularity and strong ecosystem, modular UI and chat components streamline development for high-performance applications.
How do React components and libraries work?
React is a declarative, component-based JavaScript library designed for building user interfaces. At its core, React abstracts the complexities of the Document Object Model (DOM) by using a virtual DOM and a unidirectional data flow. This allows developers to write predictable UI logic through encapsulated components, where each component’s state and props determine its rendering behavior.
React components are highly composable and reusable, making them ideal for building scalable frontend architectures. State management is localized by default (via useState or class state), but for more complex applications, state can be elevated and managed globally using libraries like Redux, Zustand, Recoil, or React’s built-in Context API.
React itself is frontend-focused and does not handle backend concerns. However, developers often integrate React with various ecosystems depending on the platform:
- React DOM is used for web applications.
- React Native is a parallel library used to build native mobile apps using the same component model.
- React Navigation is commonly used in React Native projects to manage app routing and navigation.
- For full-stack functionality, React apps are typically paired with backend services or APIs (e.g., REST, GraphQL, Firebase, or PubNub) to handle data persistence, real-time messaging, and business logic.
One of React’s greatest strengths is its thriving open-source ecosystem. The combination of a low learning curve for JavaScript developers, powerful third-party libraries, and an active community has solidified React as the dominant choice for frontend development.
At PubNub, we’ve extended React’s capabilities by developing a suite of modular UI and chat components tailored for real-time, interactive applications. These components abstract away the complexity of building reliable, scalable in-app chat, presence, and virtual collaboration spaces. Built with performance and extensibility in mind, our components seamlessly integrate with React applications—whether web-based or mobile via React Native.
In this guide, we’ll explore:
- The foundational principles of React and how they apply to large-scale apps
- Key architectural patterns for state and effect management
- How PubNub’s React components accelerate development of real-time features
- Best practices for building performant, scalable, and maintainable UIs
Whether you’re scaling a chat app to millions of concurrent users or building rich collaboration interfaces, understanding how to leverage React’s ecosystem—and extend it with tools like PubNub—is critical for delivering modern, responsive experiences.
A brief React 101 tutorial
React combines rendering logic with other facets of UI logic, making it straightforward and efficient. It works on the idea that markup and logic can be grouped into sections, which we call components, based on goals or specific concerns.
React handles rendering and component state, but real-time features like messaging and live updates need external solutions. PubNub integrates with React for scalable real-time state management, ensuring efficient data synchronization across users and devices. React focuses on UI, so PubNub simplifies adding real-time capabilities without complex backend infrastructure for chat, gaming, and collaboration apps, with Node.js as a server-side environment.
React is fast and scalable, making it ideal for real-time applications. It uses a Virtual DOM and efficient diffing to optimize speed by minimizing recalculations on the real DOM. A key benefit is that React updates only the necessary parts of the actual DOM in an optimized way, improving performance. React also supports server-side rendering (SSR), outperforming client-side rendering in initial load time and SEO. Its component-based structure allows for easy expansion and maintenance, enabling developers to build and Increase application capacity over time.
What You Need to Use React Libraries?
React works off Javascript and the DOM, and it is used in designing interfaces. To get the most out of React, it can be helpful to make sure you are familiar with the following things:
- Basic HTML and CSS
- Basic Javascript
- The DOM
- Javascript ES6 Syntax
- Node.js
- GitHub
Basic knowledge of all of the above will make it easier to understand and use React successfully.
JSX and React Components
JSX (JavaScript XML) is a syntactic extension to JavaScript that enables developers to author UI components using a declarative syntax that closely resembles HTML. While it may look like HTML, JSX is not HTML—it is transpiled into JavaScript function calls, typically React.createElement, during the build process. This transformation is handled by tools like Babel, which compiles JSX and modern JavaScript (ES6+) into backward-compatible JavaScript suitable for production environments.
Why JSX Matters in Production-Grade Applications
In traditional web development, separating HTML, CSS, and JavaScript into different files has been considered good practice for maintainability and performance. However, React challenges this separation by co-locating markup (via JSX), logic (JavaScript), and sometimes styles (CSS-in-JS) into self-contained components. This shift enables better encapsulation, enhanced reusability, and more predictable rendering behavior—critical factors for maintaining large-scale frontend architectures.
JSX isn't merely syntactic sugar for convenience; its deeper value lies in aligning UI declarations with the application's stateful logic. When compiled, JSX expressions become plain JavaScript object trees, which React’s virtual DOM uses to efficiently compute and apply UI diffs.
gets transpiled by Babel into:
This transformation is performed during build time, ensuring no JSX code reaches the browser. It also opens the door for build-time optimizations, such as tree-shaking, constant hoisting, and dead-code elimination, depending on your bundler setup (e.g., Webpack, Vite, or ESBuild).
Component Composition and Visual Semantics
One of JSX's strengths is that it brings visual clarity to component hierarchies. Developers can treat JSX as a domain-specific language for describing UI structures, enabling expressive and readable templates. This is particularly beneficial when working with nested components or building complex, reusable UI systems.
While this looks like markup, every tag is ultimately a function call or a class instantiation with props—maintaining the purity and functional nature of React applications.
Tooling and Compatibility
Babel plays a crucial role in React projects, especially in production pipelines. Besides JSX compilation, Babel ensures compatibility with a wide range of browsers by transpiling modern JavaScript syntax (e.g., async/await, optional chaining) to ES5 or the appropriate target level defined in your Babel config.
This is vital in enterprise-grade apps where browser support matrices are diverse and regressions in UI behavior can have business-critical impact.
JSX is not just syntactic sugar—it’s a productivity enabler and a foundational pillar of the React ecosystem. Understanding its compilation mechanics and implications on performance, testability, and maintainability is essential for building and scaling robust frontend systems.
In production, JSX enables:
- Tight coupling of logic and presentation within components
- Enhanced readability and maintainability
- Compile-time optimizations for rendering performance
- Predictable component behavior due to unidirectional data flow and declarative syntax
What are React components?
React components are reusable code blocks that help break down the UI into manageable pieces, improving both development efficiency and maintainability.
Components are either functional or class-based.
Functional components are stateless, accepting props and returning a React element, making them ideal for presenting UI.
Class components manage internal state and support lifecycle methods, essential for handling dynamic behavior, side effects, and more complex logic that requires tracking component lifecycle events (like mounting, updating, and unmounting).
Components are encapsulated, allowing isolated updates without affecting others, making large-scale applications fast, scalable, and easy to maintain.
Excessive use of class components can lead to performance and maintainability issues, so functional components are preferred unless state management or lifecycle methods are needed.
Use PubNub’s React components to build great chat applications
PubNub specializes in enabling developers to build fully-featured chat solutions, so it makes sense that we have created a comprehensive library UI and chat React Components to ensure an easier building experience and faster time to market for developers who build with us. These components are now available as a beta release, so if you'd like to be a tester and have the opportunity to provide feedback, check out our docs for more detailed descriptions of the implementation process, along with best practices.
PubNub React component library
Working with PubNub and using our pre-built components will significantly save you dev time, money, and labor, all while making it easier to scale and grow your application. There’s no need to build additional components or basic architecture, when we’ve already done the work for your React application needs.
Using our components library is one of the best ways to add features to your chat without dealing with the complexities of the low-level infrastructure. Some key benefits to using our React chat components when building with PubNub include:
- Reduced implementation time: You can quickly develop production-ready apps with drag-and-drop components.
- Rich chat features: These components enable features like typing indicators, read receipts, reactions, and more without you having to write complex code.
- Flexibility and customizability: Customize component design and add custom components to extend functionality.
- Scalability: In regular PubNub fashion, these components have no concurrency limits, which means you can grow your chat quickly and reliably as-needed. We have made it easy to implement and change additional features as your use case, users, and monthly usage expand.
- UX themes: There are built-in light and dark themes for various use cases like group, support, and live event chats. There is extra customization available with CSS variables.
We include all of the necessary features to build a great chat experience with our reusable components, such as:
- User and channel metadata: fetch metadata about users, channels, and memberships from PB Objects storage using custom hooks.
- Subscriptions: automatically subscribe to the current channel, with optional subscriptions to other channels and groups.
- Messages: publish and listen to text messages, and fetch history for each channel.
- Presence: fetch present users, listen to new presence, and publish presence events.
- Typing indicators: display typing indicators as text notifications or messages.
- Message reactions: publish and display message reactions (like emojis) for each message.
With these React components, you have the base to build any type of chat available, like live event chat lobbies, multiplayer in-game chat, or a HIPAA-compliant doctor-patient chat. The design, features, and use case can then be customized to fit your needs.
Why PubNub vs. Stream or Firebase?
PubNub's components offer several advantages over competitors like Stream or Firebase. PubNub’s architecture is specifically built for high-concurrency environments, allowing you to scale your chat solution without worrying about performance bottlenecks. While Firebase or Stream may provide basic chat functionality, PubNub’s components are optimized for scalability with a focus on real-time messaging performance, ensuring that your application can handle thousands—or even millions—of concurrent users seamlessly.
Example tutorial for building React applications
React is an open-source platform with a lot of great documentation and sources available on the subject. React’s official website includes many in-depth tutorials that are extremely helpful in getting set up and learning how to create and run React apps. Their tutorials range from building a simple “hello, world!” application to building an in-browser game.
Our team has also written and provided many great tutorials for building chat applications in React. Check out some of them below:
We’ve also built a sample chat app with PubNub’s React components, and provided the GitHub REPO.
Want to build with PubNub? contact sales to get started.
