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Imagine building a mobile app that works on both iOS and Android–without maintaining two separate codebases. Being one of the top mobile app development platforms, React Native makes this possible. The power lies in the React Native architecture.
React native bridges the gap between cross-platform development and native user experiences by combining JavaScript with native performance.
This blog breaks down React Native’s architecture. That is, everything from its core components like JavaScript thread and native modules to its rendering process. Plus, I’ll explain how the React Native experts build cross-platform apps with it. Let’s begin.
What is React Native Architecture?
React Native’s architecture enables developers to build cross-platform mobile apps using JavaScript while delivering near-native performance. So JavaScript code can communicate with the native parts of a mobile device–like the camera, buttons, and screen layouts–with ease.
Unlike traditional hybrid frameworks, React Native doesn’t rely on WebView. Instead, it executes JavaScript logic in a separate thread and communicates with native modules via a bridge.
Main Components of React Native Architecture
React Native works by connecting JavaScript code with native mobile features. Let’s understand the key parts of how React Native works under the hood.
JavaScript Layer (React & State Management)
The JavaScript layer executes application logic using React components and state management systems (Redux, Context API). It processes business logic, handles UI rendering through JSX, and runs on optimized engines like Hermes for better performance.
This layer remains platform-agnostic, allowing code reuse across iOS and Android.
JavaScript Interface (JSI)
JSI replaces the legacy bridge with direct, synchronous communication between JavaScript and native code. It eliminates JSON serialization overhead and enables lazy loading of native modules.
Unlike the bridge, JSI allows JavaScript to hold references to native objects. It improves performance in high-frequency interactions.
Fabric (New Rendering System)
Fabric is React Native’s new renderer, written in C++ for cross-platform consistency. It enables synchronous UI updates by allowing JavaScript to directly control native components. The optimized Shadow Tree reduces layout calculation time, while the unified core ensures identical behavior across iOS and Android.
TurboModules
TurboModules optimize native module usage by loading them on-demand rather than at startup. They use Codegen to generate type-safe interfaces, reducing runtime errors. This system also simplifies native module maintenance through auto-linking and clearer dependency management.
Native Layer (Platform-Specific Code)
The native layer consists of platform-specific code (Swift/Obj-C for iOS, Kotlin/Java for Android) that interfaces directly with device APIs. It handles hardware operations, system services, and performance-critical tasks that JavaScript cannot execute efficiently. This layer ensures full access to native capabilities.
For example, if you press a button, the Native thread sends a message to the JavaScript thread. If your JavaScript code wants to show a new screen, it sends a message back to the Native thread.
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How Does React Native Architecture Work?
React Native’s architecture enables JavaScript code to control native mobile interfaces. It does that by establishing a structured communication pipeline between different runtime layers. Here’s the operational flow.
JavaScript Layer Initialization
The JavaScript engine (Hermes/JavaScriptCore) loads the app bundle. React components parse JSX into virtual DOM. Business logic executes here, while state management systems (Redux/Context) handle data flow. This layer remains platform-agnostic.
JavaScript-to-Native Communication (JSI)
JSI enables direct synchronous calls between JS and native code. It replaces JSON serialization with C++ object references. Native modules load lazily. JS can now invoke native methods without bridge delays.
Rendering Process (Fabric)
Fabric’s C++ core converts React elements to platform-specific UI. It computes layouts synchronously using an optimized shadow tree. The renderer bypasses the old asynchronous bridge, enabling immediate UI updates.
Native Module Interaction (TurboModules)
TurboModules load native code on-demand via type-safe interfaces. Codegen generates binding code during build. This eliminates startup overhead and provides better type checking between JS and native layers.
Native Layer Execution
Platform-specific code (Swift/Kotlin) handles hardware interactions. The UI thread manages rendering while background threads process sensors/network. Native components receive direct commands from Fabric’s renderer.
React Native offers a streamlined architecture that combines React’s development speed with near-native performance characteristics.
To leverage this process to its ax benefits, it would be ideal to opt for a professional React Native app development company. Our experts explore the project requirements and see how every component of this architecture can be executed to the tee.
Problems with the Old Bridge-Based Architecture
The Bridge was useful, but it had some serious downsides that affected performance and developer experience:
Asynchronous Communication
The legacy bridge enforced asynchronous messaging between JavaScript and native threads, introducing unpredictable delays. This made real-time interactions (like gesture handling) difficult to implement smoothly.
Serialization Overhead
Every cross-platform call required JSON serialization/deserialization, creating significant CPU overhead. Complex data structures suffered particularly poor performance due to repeated encoding/decoding cycles.
Harder to Debug
The opaque bridge layer obscured the JavaScript-to-native communication flow. Developers struggled to trace issues across the serialization boundary, often requiring native debugging tools alongside JavaScript consoles.
Performance Bottlenecks
The single-threaded bridge queue caused congestion during high-frequency operations (e.g., animations or sensor data). This resulted in dropped frames and unresponsive UIs under heavy load.
These issues led to the creation of the new React Native architecture, designed to be faster, smoother, and more modern.
Benefits of the New React Native Architecture
The changes in React Native’s internal structure aren’t just technical upgrades – they directly impact how apps behave and how easy they are to build and maintain.
This shift focuses on solving real problems that developers and users have faced with earlier versions, making apps more responsive, efficient, and easier to scale over time.
Better Performance
Thanks to JSI, TurboModules, and Fabric, the app runs faster, responds quicker, and feels smoother. This is especially helpful for apps with complex interfaces or frequent updates.
Easier Debugging & Maintenance
With synchronous and direct communication, developers can track issues more easily. The cleaner structure also makes the codebase easier to understand and maintain.
More Native-Like Experience
Fabric enables smoother animations and transitions, making the app feel more like a true native app – not a web view.
Flexible and Future-Ready
The modular setup allows teams to swap or upgrade parts of the system without affecting the whole app. This makes your app more adaptable to future improvements.
With these improvements, React Native feels faster, more flexible, and closer to the native app experience than ever before.
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FAQs for React Native Architecture
Do I need to rewrite my entire app to use the new React Native architecture?
No, you don’t need to rewrite everything. React Native supports incremental migration, which means you can start adopting parts of the new architecture (like TurboModules or JSI) without fully overhauling your existing codebase.
Is the new architecture compatible with all React Native libraries?
Not all third-party libraries are fully compatible yet. Libraries that depend heavily on the old bridge might require updates to support the new architecture. It’s a good idea to check each library’s documentation or GitHub issues to see if they support Fabric and TurboModules before migrating.
Does using the new architecture improve app startup time?
Yes, especially with TurboModules, which load native modules only when needed (on-demand). This reduces the initial load, speeds up the startup process, and results in a faster, smoother app experience – particularly important for apps with a large number of native dependencies.
Is backward compatibility affected when upgrading?
React Native maintains backward compatibility, but older modules relying on the bridge may need updates. The “New Architecture” opt-in allows gradual migration.
Let’s Summarize
React Native’s architecture has evolved significantly, addressing past limitations with new performance and development efficiencies.
The new architecture replaces the legacy bridge with JSI, introduces Fabric for smoother rendering, and optimizes native modules with TurboModules. That helps deliver near-native performance without sacrificing developer productivity.
Whether you’re building a new app or optimizing an existing one, learn how to leverage React Native’s full potential. Hire our React Native professionals today!
