React Native 0.75 to 0.76 Upgrade: Key Insights Explained

React Native has consistently led the way in mobile app development by providing developers with a strong framework for creating cross-platform apps. The switch from React Native 0.75 to 0.76 brought about a few new features, performance enhancements, and bug fixes that help make mobile apps quicker and more dependable. Here is a detailed look at React Native 0.76's new features and why you should update them.

Old vs New Architecture

Old Architecture

Threads in the Old React Native Architecture

• JavaScript Thread: Handled the app's JavaScript code and logic. 
• Main/UI Native Thread: Rendered the app's native components on the device. 
• Shadow Thread: Managed layout calculations using the Yoga layout engine. 

Bridge-Based Communication

Communication between JavaScript and native components relied on a bridge. This bridge converted data into JSON and sent it asynchronously between threads. While functional, this approach caused several issues:

• Performance Issues: Animations were jerky, and frames were skipped, failing to maintain 60 FPS. 
• Memory Overhead: Duplicating nodes and DOM elements increased memory usage. 

Problems with the Old Architecture

• Delays in Communication: JSON conversion created noticeable lags. 
• Blocked Threads: Important tasks like rendering were delayed by less critical operations. 
• Inefficient Memory Use: Maintaining separate DOM trees for JavaScript and Native consumed unnecessary memory.

New Architecture

Components of the New Architecture

The new architecture addresses these challenges with modernized components and improved performance: 

JavaScript Interface (JSI)

• What It Does: Replaces the bridge with a direct interface between JavaScript and native code. 
• How It Works: Allows JavaScript to hold references to native objects, enabling synchronous communication. 
• Benefits: 
• Faster execution and reduced latency. 
• Supports any JavaScript engine, extending compatibility to platforms like smart TVs and wearables. 
• Seamless cross-platform development. 

TurboModules

• What It Does: Implements native modules using JSI and C++. 

Key Features: 

• Enables both synchronous and asynchronous execution. 
• Lazy-loaded modules improve startup time and memory usage. 

Benefits: 

• Better performance. 
• Faster app launches. 
• Efficient memory management.

Codegen

• What It Does: Automatically generates strongly typed interfaces to bridge JavaScript and C++. 

How It Works: 

• At build time, Codegen ensures type contracts between JavaScript and C++ are correct, avoiding runtime errors. 
• Pre-defined contracts allow direct method calls without interpretation. 

Benefits: 

• Fewer runtime errors. 
• Improved developer productivity. 
• Faster execution. 

Fabric Renderer

• What It Does: The new rendering engine that replaces the old UI renderer. 

Key Features: 

• Introduces an immutable tree of UI states. 
• Thread-safe updates for concurrent rendering. 
• Background updates without blocking the main thread. 
• Smooth transitions with interruptible low-priority tasks. 

Benefits: 

• Enhanced rendering efficiency. 
• Better UI responsiveness. 
• Improved performance for complex interfaces. 

Hermes Engine 

• What It Does: A JavaScript engine optimized for running JavaScript code directly on devices. 

Key Features: 

• Works seamlessly with JSI. 
• Lightweight and fast. 

Yoga Layout Engine

• What It Does: A cross-platform layout engine, retained from the old architecture, now better integrated with Fabric for layout calculations. 

CODE LEVEL CHANGES

React Native 0.76 introduces two significant new style properties: boxShadow and filter. 
 
style= {{ boxShadow: "10px 10px 15px rgba(0, 0, 0, 0.5)", filter: "blur(5px) brightness (0.8)"}} 
 
Before the introduction of boxShadow and filter properties in React Native 0.76, developers needed to rely on workarounds to achieve similar effects, often through third party packages.

Example of box shadow source

You can add movable shadows to items by modifying their size, color, blur, and position using the `boxShadow` property. It gives you complete control over the appearance of the shadow. For an in-depth overview and a live demo for checking it out, see the MDN documentation. 

The `filter` property gives items visual effects, such as creating blurring and shadows or altering brightness, saturation, and hue. It offers a wide range of innovative styling possibilities. For more information and to view an interactive demo, visit the MDN documentation. React Native, for example, shows how filters may add various effects to a hot dog image.

Performance Improvements

The focus React Native 0.76 places on performance optimization is one of its main features:  

• Faster Rendering: More responsive user interfaces and fluid animations are guaranteed by streamlining the rendering pipeline.   
• Memory Efficiency: React Native apps now have a smaller overall memory footprint thanks to the patching of memory leaks found in the previous version.   
• Improved App Startup Time: Even on older devices, apps load more quickly thanks to initialization sequence optimizations.   

By making apps more dependable and resilient, these upgrades improve the experience for both developers and end users.

Dependency Updates

React Native 0.76 maintains compatibility with the latest tools and libraries by adjusting its dependencies: 

• React Core Update: Due to the framework's support for the most recent stable version of React, new features and enhancements are now available.   
• Library Compatibility: To avoid possible conflicts, several widely used libraries have been modified to function flawlessly with 0.76. 

Maintaining fundamental dependencies lowers the chance of security flaws and guarantees a more efficient development process.

Improved Tools for Development

Tools and features targeted at enhancing the developer experience are introduced in React Native 0.76:

• Better Debugging: Due to enhanced error messages and debugging support, problems can be identified more easily during development. 
• Improvements to TypeScript and Flow: Stronger type-checking guidelines help programmers identify mistakes early and keep codebases cleaner.   

These tools encourage better coding techniques in addition to saving time during development.

New Features for Developers

React Native 0.76 offers additional features along with fixes and optimizations. 

• Improvements to the Hermes Engine: The Hermes JavaScript engine has been enhanced to increase compatibility with contemporary JavaScript features and improve performance. 
• Navigation Improvements: Updated navigation components offer better gesture support and seamless transitions, enhancing the user experience.
• Extended Native Module Support: React Native's capabilities have been expanded by making it easier for developers to create and integrate native modules.

Platform-Specific Updates

React Native 0.76 keeps improving platform-specific features while strengthening its cross-platform capabilities:

• iOS: Complete native component support for SwiftUI facilitates the implementation of contemporary iOS designs. Compatibility with the most recent versions of the iOS SDK and Xcode.
• Android: Improved compatibility with Material Design 3, guaranteeing that apps appear consistent and up to date.

Compatibility with the most recent Android API versions aids developers in making their apps future-proof.

Improvements in Accessibility

In this update, React Native's dedication to diversity is evident:

• Better Screen Reader Support: If you integrate accessibility technologies more effectively, your apps will be usable by all audiences. 
• Focus Management: Using assistive technologies in apps with improved focus control is more straightforward.

Deprecations and Bug Fixes

Without fixing current problems, no update is complete. Several issues that were reported in 0.75 have been fixed in 0.76, including:  

• UI errors and inconsistencies in intricate designs.   
• Crashes on some devices when switching between navigation modes.   

A few earlier APIs will also be deprecated with React Native 0.76, providing developers with advance notice to update their codebases.

The Key Reasons for Upgrading to React Native 0.76

• Better Performance: The default new architecture and optimized Metro bundler allow for up to 15 times faster build times, smoother load times, and increased app efficiency, guaranteeing an excellent user experience.   
• Increased Developer Productivity: New DevTools facilitate cleaner, more effective development by streamlining debugging and coding with persistent breakpoints and supporting contemporary React features like automated batching.   
• Future-Ready Framework: The upgrade improves native module communication, improving performance and reliability while lowering technological debt, conforming to contemporary React concepts, and facilitating the smooth inclusion of future features.  

React Native 0.76 provides the performance, capabilities, and futureproofing needed to quickly create high-caliber mobile applications.

Conclusion

More than just a standard update, React Native 0.76 is a significant advancement that will enable developers to produce outstanding mobile experiences. This version further solidifies React Native's standing as a leading option for cross-platform app development, offering accessibility capabilities, new developer tools, and speed improvements.

If you haven't already, now is the perfect moment to upgrade and take advantage of all that React Native 0.76 has to offer!