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Wednesday, March 1, 2023

Top 25 React Native interview Questions Answers

Hello guys, if you are preparing for React Native Developer interview and looking for common React Native Interview questions and answers then you have come to the right place. Earlier, I have shared best free online courses to learn React Native and in this article, I am going to share 25 React Native Questions you can prepare for any Job interview. Mobile application development has advanced at a rapid pace in the last decade. As the usage of mobiles has increased immensely, more and more companies have figured that mobile applications are the future. So because of this increasing demand for mobile applications, the technology has advanced to keep up with the expectations.  

The mobile operating system is dominated by Android, followed by IOS. Apart from these two operating systems, there are a few other operating systems as well. React native is one of the most popular and widely used mobile application development frameworks.

It is used to create cross-platform mobile applications, meaning, applications that can run on multiple platforms. Because of this reason, and many others, React native is used widely. Today, React native is one of the most popular names in the development community.

25 React Native Interview Questions with Answers

React native has a huge job market today. These jobs are high-paying as well. But clearing interviews for such jobs can be tough and tricky. In this article, we will list 20+React native questions that are usually part of React native interviews.

1. What is React Native and how is it different from React.js? What are the similarities?
Answer: React native is an open-source cross-platform mobile application development framework. It is written in JavaScript and is used to create applications that can run on multiple platforms such as Android, IOS, Windows, etc.

The biggest difference between React Native and React.js is that the latter is used to develop web applications while the former is used to develop mobile applications natively. Another difference is that React Native does not use HTML.

Both, React Native and React.js have component-based architecture. Both of them have lifecycle methods and hooks.

Top 25 React Native interview Questions Answers

2. Why should we use React Native?

There are multiple reasons to use React Native but given we have limited time, here are top 4 reasons to use react native for app development
1. React native applications are cross-platform. We do not need to develop different applications for different platforms.

2. React native comes with live and hot reloading features. These features are very helpful during development.

3. Third-party plugins can easily be used with React native.

3. What is the state of React native?
A: State is a type of data in React native that is used to control a component.

4. Explain the bridge in React Native?
A: Bridge in React native is a connection or a layer to connect the JavaScript side of the React native application with the native side (vice-versa).

5. Explain ListView in React Native?
A: ListView is a view component in React native. It contains a list of scrollable items that are displayed vertically.

6. Which module can be used to detect the platform in which the application is running?
A: The platform module can be used to detect the platform.

7. List the various ways of styling React native applications?
The various ways of styling React native apps are: using stylesheet, Styled components, and style props.

8. How can you optimize a React native application?
Here are a couple of tips to optimize a React Native application:
1. Reduce image size. Use compress images and graphic elements.

2. Make use of pure and memorized components.

3. Avoid storing raw JSON data.

4. Try to minimize the application size.

5. Try to optimize native libraries.

9. What is the difference between React native's flexbox and web flexbox?
A: The default value of the flex-direction property is different in React native. In web, its default value is "row" while in React native, it's "column".

10. Explain how to handle input in React native.
A: React native provides TextInput for handling inputs in React native. It is a core component. It provides an onChangeText prop that takes a function as its value and that function is called every time the text changes. Another prop, called onSubmitEditing is used to submit the text. It also takes a function as its value.

11. Explain a way to center a view component on screen?
A: There are many ways to center a view component on-screen in React native. The most common one is by using Flexbox. We can center it by using the justify-content and align-items properties of the flexbox.

12. What is prop drilling? How to avoid it?
A: In React native, when we pass props from the parent component to a child component that is nested deep inside, other components that are in between the parent and that child component also end up owning that props. This concept is called prop drilling.

Prop drilling can be avoided by Context API or Redux. Other ways are composition and rendering props.

13. Name all the core components of React native?
A: The core components of React Native are: <View>, <Image>, <Text>, <TextInput>, and <ScrollView>.

14. What is the equivalent of <div> in React native?
A: Equivalent of non-scrolling <div> is <View> while the equivalent of scrolling <div> is <ScrollView>.

15. How to store sensitive data in React Native?
A: There is no in-built way of storing sensitive data in React native. Both Android and IOS have their own solutions for this: Secure shared preference and Keystore in Android, and Keychain services in IOS.

16. What are Higher-Order Components?
A: HOC or Higher-Order Components is a technique in which component logic can be reused. In such functions, a component is passed and a new element is returned.

17. How to enable the camera in React native?
Camera permission must be asked in Android, like this:

<uses-permission android:name="android.permission.CAMERA" />

In IOS, info.plist should be updated with a usage description to enable the camera use, like this:

<key>NSCameraUsageDescription</key> <string>Description</string>

18. Why use Redux in React Native?
A: State is an important part of React native applications. Redux is a state management library used to create a global state for an entire application. If the application is big and complex, Redux is a very good option to maintain its state.

19. How will you make HTTP requests in React native?
A: Axios is a very good option to make HTTP requests. It is a third-party library that is easy to install and use.

20. What are the disadvantages of using React Native?

1. React native depends on third-party libraries.

2. There are security risks.

3. It has single-threaded interfaces.

4. It does not support all natives APIs,

5. Memory management is poor.

21. Name the timers used in React native.

1. setTimeout

2. clearTimeout

3. setInterval

4. clearInterval

5. setImmediate

6. clearImmediate

7. requestAnimationFrame

8. cancelAnimationFrame

22. What are hooks? Name some of the commonly used hooks?
A: Hooks are in-built functions that let us use state and other features without using classes.

Some of the commonly used hooks are useState, useEffect, and useDispatch.

23. Why use hooks in React native?
A: Previously, It was not possible to use state in a functional component. We had to create a class component for using state. But with hooks, we can use the state as well as lifecycle methods in a functional component.

That's all about the 20+ React native questions that are commonly asked in an interview. Though the interview can be tough, you can clear it if you research the questions mentioned in this article. Moreover, in a React native interview, JavaScript plays an important part. So if you are preparing for a React native interview, be sure to go through modern JavaScript concepts as well.

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Thanks for reading this article so far. If you like these React Native Interview Questions, then please share them with your friends and colleagues. If you have any questions or feedback, then please drop a note.

P. S. - If you want to learn React Native in depth and looking for best online resources then you can also check out these React Native online courses from Udemy, Coursera, Pluralsight, and Educative where I have shared best React Native courses for both beginners and intermediate App developers. 

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