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React Native · Question Set
Native Modules & Bridging interview questions for placements and exams.
Questions
14
Included in this set
Subject
React Native
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Difficulty
Mixed
Level of this set
Go through each question and its explanation. Use this set as a focused practice pack for React Native.
Native modules allow React Native apps to access native platform features like camera, sensors, or Bluetooth using Java or Swift. They bridge the gap between JavaScript and native environments so both can communicate seamlessly.
For complete preparation, combine this set with full subject-wise practice for React Native. You can also explore other subjects and sets from the links below.
The bridge is the communication layer that sends messages between the JavaScript thread and native threads. This mechanism ensures that native features and UI elements can be controlled using JavaScript APIs.
JNI (Java Native Interface) allows Java code to interact with C or C++ libraries. React Native internally uses JNI to enable deep integrations between JavaScript and native performance modules.
In Android native modules, methods annotated with @ReactMethod become accessible from JavaScript. These methods are exported automatically when the module is registered with ReactPackage.
The RCT_EXPORT_METHOD macro exposes an Objective-C method to the JavaScript runtime. It allows React Native’s bridge to call native iOS functionality from JavaScript code.
React Native maintains a separate JavaScript thread where all JS logic executes. This prevents blocking the UI thread and allows smooth animations and user interactions.
The React Native bridge serializes function calls and arguments into JSON messages. These messages travel asynchronously between JavaScript and native threads for two-way communication.
Native view managers allow developers to create custom UI components using native platform views. They expose these views to JavaScript so React Native can render them like regular components. Each view manager defines properties and methods accessible from JS.
JSI allows JavaScript to call native code directly without using asynchronous JSON serialization. It improves performance by removing the overhead of message passing, enabling synchronous function calls and direct memory sharing between JS and native code.
Native modules use the RCTDeviceEventEmitter on iOS or ReactContext’s sendEvent method on Android to emit events. This is useful when native code needs to notify JS about background tasks, downloads, or hardware events.
A custom native module is useful when you need a feature not yet supported by React Native or third-party libraries. For example, integrating a specialized Bluetooth SDK, using advanced camera APIs, or controlling device audio routing directly on Android.
The old bridge was asynchronous and relied on JSON serialization, which created latency between JavaScript and native layers. It also struggled with large data transfers like images or audio streams. JSI and Fabric now address these limitations.
ReactPackage is an interface that exposes a list of native modules and UI components to the JavaScript side. Every custom native module must be added inside the createNativeModules() method of a ReactPackage implementation.
TurboModules use the JavaScript Interface (JSI) to directly call native code without serializing messages. This reduces latency and significantly improves communication speed between JS and native layers.