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React Native · Question Set
Basics & Core Concepts interview questions for placements and exams.
Questions
13
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.
Platform.select() lets you define different implementations for iOS and Android. It’s commonly used when certain UI or logic should vary between platforms.
const padding = Platform.select({ ios: 20, android: 10 });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.
React Native class components share lifecycle methods with React. Key ones include: - **componentDidMount()** → called once after initial render, good for fetching data. - **componentDidUpdate()** → runs after updates. - **componentWillUnmount()** → cleanup work like clearing timers or listeners. These methods are now replaced by hooks like useEffect in functional components.
React Native allows cross-platform development, saving time and cost by sharing code between iOS and Android. It uses native components for a smooth UI, supports live reload, and has a large ecosystem of prebuilt libraries. It’s popular for startups and enterprises alike because it offers both speed and near-native performance.
JSX allows developers to describe UI components in a declarative way. It looks similar to HTML but compiles down to JavaScript function calls. In React Native, it represents <View>, <Text>, and other native components.
Some challenges include limited support for heavy native animations, dependency on third-party libraries, and occasional compatibility issues with new platform APIs. Complex apps may need native modules for performance-critical tasks. Despite this, React Native remains powerful for most business applications with moderate native needs.
React Native is a JavaScript framework that allows developers to build native mobile applications for iOS and Android using the React library. It bridges JavaScript with native platform components, offering near-native performance and a single shared codebase.
React Native provides a set of built-in core components like <View>, <Text>, <ScrollView>, and <Image>. <Paragraph> is not one of them; for styled text, you combine <Text> components instead.
React is a library for building web interfaces using HTML elements like <div> and <p>. React Native replaces these with mobile-native components such as <View> and <Text>, allowing JavaScript to render actual native UI components.
The React Native bridge enables communication between the JavaScript thread and native threads. It converts JS commands into native code (Objective-C, Swift, Java, or Kotlin), which is then executed by the platform.
Props are inputs passed to components, similar to function arguments. They are read-only. State is local data managed within the component and can change over time, causing re-renders.
The useState hook lets you add internal component state to functional components. It returns a pair: the current state value and a function to update it.
const [count, setCount] = useState(0);
React Native uses React’s virtual DOM concept to decide which parts of the UI need updating. When state or props change, React recalculates a virtual representation and compares it with the previous one. Only changed elements are sent to the native side through the bridge, minimizing performance cost. Understanding this helps developers optimize components and avoid unnecessary re-renders.
Class components use ES6 classes and can access lifecycle methods like componentDidMount. Functional components are plain functions that return JSX and rely on hooks (like useState and useEffect) to manage state and side-effects. Functional components are now the standard approach—they are shorter, easier to test, and better optimized by React.