Are you in the preparation phase for a React Native interview? Well, then, you've come to the right place. Both seasoned developers or newcomers to the mobile app development world need to be well-prepared. After all, landing the job of one's dream is not an easy task. This blog showcases the top 30 React Native interview questions.
These React Native questions have been compiled to help aspirants ace their next interview. It covers questions from the fundamental concepts to highly advanced techniques. These interview questions tap into many topics frequently asked by hiring managers during an interview. Let's dive in to brush up basic knowledge and give confidence a boost!
Want to become React Native Developer? Enroll in igmGuru's React Native course program now.
The first segment contains commonly asked React Native interview questions. These React Native questions are highly deemed and definitely some of the most frequently asked ones.
Answer: React is one of the most popular JavaScript (JS) libraries. It is used extensively for building user interfaces (UIs), especially for web applications. React Native, on the contrary, is a popular framework. It employs React for building native mobile applications. React employs CSS and HTML, whereas React Native employs APIs and native components.
Answer: props is the short form for properties. These are utilized to stream data from a parent component to a child component. state is employed for managing dynamic data that has an effect on the rendering of components. state is managed within the component, where props are immutable and offered by the parent.
Answer: Flexbox refers to a layout model. It is utilized for designing flexible and responsive layouts. In React Native, it is used for aligning and positioning components. Some of its main properties are justifyContent, flexDirection, flex and alignItems.
Answer: ScrollView displays a horizontal or vertical scrollable view, which is apt for the smaller lists of items. FlatList, however, is optimized especially for large lists of data. It offers performance improvements and efficient rendering via recycling of views and lazy loading.
Answer: Expo pertains to a platform and framework for universal React apps. It contains a suite of tools built especially around React Native. This set of tools aid developers in building, deploying, and iterating faster on the apps. Expo offers a managed workflow with many pre-configured services and libraries to simplify development.
Related Article- React Native Tutorial
These are some of the most commonly posed React Native technical interview questions. Hiring managers often try to understand a person's technical mindset and thus, these questions come forward.
Answer: The React Native bridge helps in building communication between native code and JavaScript. It serializes all JSON messages. After this, they are passed between the native thread and the JavaScript thread. This enables JS to easily call native modules and vice versa.
Answer: Performance optimization is achieved in React Native via multiple techniques like. These include-
Answer: State management is handled in large React Native apps by utilizing libraries such as MobX, Context API or Redux. These tools aid in the management and centralization of app state. This renders it easier to debug and maintain. Redux offers a more predictable state container, whereas MobX leans towards a reactive approach.
Answer: Higher-order components, often simply called HOCs, are functions. These take a component and then return a new component having additional behavior or props. They are employed for logic abstraction or code reuse. A perfect example is-
const withLogging = (WrappedComponent) => { return class extends React.Component { componentDidMount() { console.log('Component mounted'); } render() { return } }; }; const EnhancedComponent = withLogging(MyComponent); |
Answer: Animations are handled in React Native by employing the Animated API. It offers a compilation of methods and components for creating smooth animations. Different libraries such as react-navigation and react-native-reanimated also provide many advanced animation capabilities.
Related Article- How To Become A React Native Developer?
Being a leading framework, React Native experts need to have coding knowledge. That is why these React Native coding interview questions play an imperative role. When studying the top React Native interview questions, make sure to revise coding questions too.
Answer: Here is the code-
import { useState, useEffect } from 'react'; const useFetch = (url) => { const [data, setData] = useState(null); const [loading, setLoading] = useState(true); const [error, setError] = useState(null); useEffect(() => { const fetchData = async () => { try { const response = await fetch(url); const result = await response.json(); setData(result); } catch (err) { setError(err); } finally { setLoading(false); } }; fetchData(); }, [url]); return { data, loading, error }; }; export default useFetch; |
Answer: Here is the code to create button
import React, { useState } from 'react'; import { Button, View } from 'react-native'; const ToggleButton = () => { const [isStarted, setIsStarted] = useState(false); const handlePress = () => { setIsStarted((prev) => !prev); console.log(isStarted ? 'Stop' : 'Start'); }; return ( Button title={isStarted ? 'Stop' : 'Start'} onPress={handlePress} /> ); }; export default ToggleButton; |
Answer:
const debounce = (func, delay) => { let timer; return function(...args) { clearTimeout(timer); timer = setTimeout(() => func.apply(this, args), delay); }; }; const log = () => console.log('Debounced!'); const debouncedLog = debounce(log, 1000); |
Answer:
const capitalizeWords = (str) => { return str.replace(/\b\w/g, char => char.toUpperCase()); }; console.log(capitalizeWords("hello world")); // "Hello World" |
Answer:
import React, { createContext, useContext, useState } from 'react'; const AuthContext = createContext(); export const AuthProvider = ({ children }) => { const [isAuthenticated, setIsAuthenticated] = useState(false); const login = () => setIsAuthenticated(true); const logout = () => setIsAuthenticated(false); return ( {children}
); }; export const useAuth = () => useContext(AuthContext); |
Here is a list of the top React Native interview questions for experienced professionals. As mentioned above, preparation is equally important for both experienced and novice aspirants. These questions will help you prepare better.
Answer: React Native employs a bridge for flawless communication between native code and JavaScript. It enables the creation of truly native apps while using JS for defining the app's UI and logic. The framework uses native components to render the UI, which offers a consistent feel and look across platforms. The bridge easily translates JS code into native API calls. This ensures responsiveness and performance.
Answer: Third-party native modules are easily integrated in a React Native project by utilizing yarn or npm. react-native link is used to link these modules. Additionally, manual linking in native project files (for instance, ios/Podfile and android/settings.gradle) are also used. Other parts of the process are handling native dependencies, writing custom native modules when needed and guaranteeing compatibility with both platforms.
Answer: Some typical issues that arise during upgrades are
These can be addressed by reading the upgrade guide thoroughly, testing extensively, using tools such as react-native-upgrade-helper, sometimes contributing patches to third-party libraries and fixing breaking changes incrementally.
Answer: Integration of native SDKs revolves around inserting the SDK to native project files (for instance, Gradle for Android and through CocoaPods for iOS). Writing a React Native bridge for exposing SDK functionalities to JS, handling platform-specific configurations and permissions, and guaranteeing correct lifecycle management and initialization are key steps. Top examples here are integrating Firebase, analytics SDKs and payment gateways.
Answer: Navigation can easily be handled via React Navigation, which offers a brilliant set of navigators such as tab, drawer and stack. Configuration is needed for deep linking in both React Navigation and the native code. This includes setting up intent filters for Android and URL schemes for iOS, along with handling incoming links in the app's entry point. These help in navigating to the corresponding screen.
Also Read- Learn React Native
Revising the top React Native advanced interview questions is a great way for experienced professionals to crack an interview.
Answer: A bridge is used in React Native architecture to enable communication between native code and JavaScript. The bridge easily serializes JSON messages, then passes them asynchronously between JS threads and native threads. This enables JS to invoke native modules and the other way around.
Answer: To implement a custom native module, create a bridge between native code and JavaScript. For Android, this incorporates crafting a Java module extending ReactContextBaseJavaModule and then registering it in a package class where ReactPackage is implemented. For iOS, this incorporates crafting a Swift class or Objective-C where RCTBridgeModule is implemented. It's then registered in the bridging header. The module methods are consequently exposed to JS via NativeModules.
Answer: shouldComponentUpdate refers to a lifecycle method. It cements if a component should re-render against state or prop changes or not. It prevents costly re-renders by returning false when updates are not needed, thus optimizing performance. React.memo serves a mirroring purpose in functional components by memoizing the component as well as skipping re-renders in case the props are unchanged.
Answer: Integrating WebViews in React Native includes utilization of the react-native-webview library. This enables embedding web content within the application. Considerations include handling communication and navigation between the React Native app and the WebView through post messages or injected JavaScript. This ensures security by dodging unsafe content and performance optimization by controlling WebView loading and caching.
Answer: Performance optimization for animations is achieved by employing the Animated API, along with libraries like react-native-reanimated. These present more performant animations since they directly run them on the native thread. There are other strategies like
Still not sure about the top React Native basic interview questions? Well, here is a list to explore!
Answer: A new React Native project is created through the React Native CLI. npx react-native init ProjectName is run here. Alternatively, Expo can be used, which is a platform and framework for universal React apps. This is by running npx create-expo-app ProjectName.
Answer: Styling components in React Native is done by using JavaScript objects. These are created via the StyleSheet API.
Answer: The useEffect hook enables in performing side effects in functional components. These include setting up subscriptions, manually updating the DOM and fetching data. A function is taken as an argument, which gets executed once the component renders. Dependencies can also be specified to control when the effect should re-run.
Answer: FlatList is used to handle simple lists, while SectionList is used for lists with section headers. Every component is optimized to handle gigantic datasets as only visible items are rendered. Grids are created through FlatList with the numColumns prop.
Answer: Central components of React Native are -
These are some of the key interview questions for React Native. If you are preparing to switch jobs or get a job, then these React Native interview questions are sure to help. Keep learning and there is no stopping before reaching success. These interview questions are a brilliant way to ensure success in this rapidly growing industry.
Course Schedule
| Course Name | Batch Type | Details |
| React Native Training | Every Weekday | View Details |
| React Native Training | Every Weekend | View Details |
