100+ React Native Developer Interview Questions and Answers

The useEffect Hook in React Native is used to perform side effects in functional components. It is similar to lifecycle methods in class components.

• useEffect Hook is used to handle side effects in functional components.

• It is called after the component has rendered and can be used to fetch data, subscribe to events, or update the DOM.

• It takes two arguments: a function that contains the side effect logic, and an optional array of dependencies.

• The function passed to useEffect is...read more

Answers to various technical questions related to React Native development.

• 1. Git rebase is used to reapply commits on top of another base tip. It is used to maintain a clean and linear project history.

• 2. Flipper is a mobile debugging tool for iOS and Android apps. It allows developers to inspect and debug their apps in real-time.

• 3. useCallback is a hook in React that returns a memoized callback function. It is used to optimize performance by preventing unnecessary re-renders...read more

Hooks are functions that allow you to use state and other React features without writing a class.

• useState() - for managing state in functional components

• useEffect() - for performing side effects in functional components

• useContext() - for consuming context in functional components

• useReducer() - for managing complex state in functional components

• useCallback() - for memoizing functions in functional components

Yes, I am familiar with the new architecture of React Native.

• The new architecture of React Native is based on Fabric, a C++ UI framework.

• It separates the UI rendering from the JavaScript thread, resulting in improved performance.

• It also introduces new features like TurboModules and JSI for better native module integration.

• The new architecture is being gradually rolled out in React Native releases.

• It requires some changes in the codebase, such as using the new TurboModules API...read more

Redux Thunk and Redux Saga are middleware libraries for Redux that allow for asynchronous actions.

• Redux Thunk is a simple middleware that allows for asynchronous actions by returning a function instead of an action object.

• Redux Saga is a more powerful middleware that uses generator functions to handle asynchronous actions and allows for more complex control flow.

• Both libraries are commonly used in React Native applications to manage state and handle asynchronous actions.

• Redux...read more

Yes, I have worked on native components.

• I have experience in creating custom native modules for React Native apps.

• I have integrated native libraries like Firebase, Google Maps, and Camera into React Native apps.

• I have used native UI components like TextInput, ScrollView, and FlatList in React Native apps.

• I have also worked with native modules for iOS and Android separately.

Redux is a predictable state container for JavaScript apps. Event loop, call stack, and callback queue manage asynchronous operations. let, const, var differ in variable scoping and reassignment. setTimeout delays execution. 'this' refers to the current context. Scoping determines variable accessibility.

• Redux is a state management tool for JavaScript apps, ensuring predictable state changes.

• Event loop manages the execution of callback functions, while call stack keeps track o...read more

Class components are ES6 classes that extend the React.Component class, while functional components are just plain JavaScript functions.

• Class components are more feature-rich and have access to lifecycle methods.

• Functional components are simpler and easier to read and test.

• Class components can have state and use lifecycle methods like componentDidMount and componentDidUpdate.

• Functional components are stateless and do not have lifecycle methods.

• Functional components can be use...read more

React Native is a framework for building mobile apps using JavaScript and React.

• React Native is based on React, but instead of rendering to the browser, it renders to native components.

• It allows developers to build mobile apps for iOS and Android using a single codebase.

• React Native provides a set of pre-built components that can be used to build the UI of the app.

• It also allows for easy integration with native code when necessary.

• React Native apps are faster and more respons...read more

State, props, Redux, AsyncStorage are key concepts in React Native. Uploading a build on TestFlight involves creating an IPA file and using Xcode.

• State is used to manage data within a component and can be updated using setState.

• Props are read-only data passed from parent to child components.

• Redux is a state management library for managing application state.

• AsyncStorage is a simple, unencrypted, asynchronous, persistent, key-value storage system.

• To upload a build on TestFlight...read more

To upgrade app version programmatically, use code push or OTA updates.

• Use code push to update JavaScript code without requiring a new binary

• Use OTA updates to update the binary itself

• Ensure the app is properly configured to receive updates

• Test the update thoroughly before releasing to users

Setting up push notifications involves configuring a push notification service, integrating it with the app, and handling notifications in the code.

• Choose a push notification service provider like Firebase Cloud Messaging (FCM) or OneSignal.

• Set up an account with the chosen service provider and obtain necessary credentials (API keys, tokens, etc).

• Integrate the push notification SDK provided by the service provider into your React Native project.

• Implement code to handle receiv...read more

My highest priority HOC components are those that handle authentication and authorization.

• Authentication HOCs like withAuthenticator and withAuthContext

• Authorization HOCs like withAuthorization and withRoleBasedAccessControl

• HOCs that handle user sessions and persistent login state

Closures in JavaScript allow functions to retain access to their lexical scope even when executed outside that scope.

• A closure is created when a function is defined inside another function.

• The inner function has access to the outer function's variables.

• Example: function outer() { let x = 10; return function inner() { return x; }; }

• Closures are often used for data encapsulation and creating private variables.

• They can also be used in asynchronous programming to maintain state.

Use props to pass data from parent component to child component, and use state to manage shared data between sibling components.

• Pass data from parent to child components using props

• Use state management libraries like Redux or Context API to share data between sibling components

• Use event emitters or callbacks to communicate between components

Redux is a predictable state container for JavaScript apps, enabling centralized state management and unidirectional data flow.

• Single Source of Truth: Redux maintains the entire application state in a single store, making it easier to manage and debug.

• Actions: Actions are plain JavaScript objects that describe changes to the state. For example, { type: 'ADD_TODO', payload: 'Learn Redux' }.

• Reducers: Reducers are pure functions that take the current state and an action as argum...read more

HOC is a function that takes a component and returns a new component with additional functionality.

• HOC is a design pattern in React.

• It allows reusing component logic.

• HOC can be used for cross-cutting concerns like authentication, logging, etc.

• HOC can be created using a function that takes a component and returns a new component.

• The new component can render the original component with additional props or wrap it with other components.

• Example: WithAuth HOC can add authenticatio...read more

React Native bridge is a communication layer between JavaScript code and native code.

• It allows React Native to interact with native modules written in Objective-C, Java, or Swift.

• The bridge sends messages between the two environments, allowing for seamless integration.

• The bridge can also be used to pass data between the two environments.

• For example, a React Native app might use the bridge to access the device's camera or accelerometer.

• The bridge can be a performance bottlenec...read more

React Native is a framework for building mobile apps using React, while React JS is for web applications.

• React Native allows developers to create mobile applications for iOS and Android using JavaScript and React.

• React JS is primarily used for building user interfaces for web applications.

• React Native uses native components, while React JS uses HTML elements.

• Example: A button in React Native is a native button, while in React JS, it's an HTML button element.

• React Native provi...read more

Call stack is used to keep track of function calls, while event loop manages asynchronous operations in JavaScript.

• Call stack is a data structure that keeps track of function calls in a program.

• When a function is called, it is added to the top of the call stack. When the function completes, it is removed from the stack.

• Event loop is responsible for managing asynchronous operations in JavaScript, ensuring that they are executed in the correct order.

• Event loop continuously chec...read more

Sorting an array and using HOC components and Flux in React Native

• To sort an array, use the sort() method

• To use HOC components, create a higher-order function that returns a component

• To use Flux in React Native, install the flux package and create actions, stores, and a dispatcher

Class components and functional components are two ways to create components in React Native.

• Class components are created using ES6 class syntax and extend the React.Component class.

• Functional components are created using JavaScript functions.

• Class components have a state and lifecycle methods, while functional components do not.

• Functional components are simpler and easier to test and maintain.

• Class components are recommended for complex components with state and lifecycle ne...read more

useState, useEffect, useContext, useReducer, useRef

• useState - for managing state in functional components

• useEffect - for side effects in functional components

• useContext - for accessing context in functional components

• useReducer - for managing complex state logic

• useRef - for accessing DOM elements or storing mutable values

The release process involves preparing the app for submission, testing, uploading to the respective app stores, and managing the release.

• Prepare the app for submission by ensuring it meets all guidelines and requirements of the app stores.

• Test the app thoroughly to identify and fix any bugs or issues before release.

• Upload the app to the Play Store and Apple Store developer consoles.

• Manage the release by setting up release notes, updating metadata, and monitoring user feedback...read more

Redux is a predictable state container for JavaScript apps. React Navigation is used for navigation in React Native.

• Redux is a state management library commonly used with React to manage application state in a predictable way.

• It helps in maintaining a single source of truth for the state of the entire application.

• Redux works by having a central store that holds the entire state tree of the application.

• React Navigation is a library used for navigation in React Native applicati...read more

Hooks are a feature in React that allow you to use state and other React features in functional components. Redux is a state management library for JavaScript applications.

• Hooks are functions that let you use React state and lifecycle features in functional components.

• Hooks provide a way to reuse stateful logic between components.

• Redux is a predictable state container for JavaScript apps.

• Redux helps manage the state of an application in a centralized manner.

• Redux uses a singl...read more

Understanding async/await in React Native is crucial for handling asynchronous operations effectively.

• Async functions return a promise, allowing the use of await to pause execution until the promise resolves.

• Example: async function fetchData() { const data = await fetch(url); return data.json(); }

• Using try/catch blocks with async/await helps in error handling: try { const result = await someAsyncFunc(); } catch (error) { console.error(error); }

• In React Native, async/await can...read more