React Interview Questions for Experienced Developers

React Native interview questions for experienced developers are designed to select candidates who are capable of building an enterprise React application. These questions are frequently asked in front-end Java developer interviews. You must be a skilled JavaScript developer who can easily create web applications using React. These experiences will assist you in qualifying for your upcoming technical interview.

In 2013, Facebook engineers introduced the React framework to simplify platform maintenance and increase traffic. React is still popular nine years later, and top tech companies use it. If you are applying for a position that requires React Native or ReactJS knowledge, review the following React Native interview questions for experienced professionals.

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Here's what we'll cover:

• React Native Interview Questions for Experienced Developers
• Technical React Interview Questions for Experienced Developers
• ReactJS Interview Questions for Experienced Professionals
• FAQs on React Native Interview Questions for Experienced Developers

React Native Interview Questions for Experienced Developers

React Native framework is best-suited for writing real and native mobile/desktop applications for iOS, Windows, and Android. It has been a favorite among top tech companies. If you are applying for senior positions at FAANG+ companies, you must practice the following React Native interview questions for experienced developers.

Q1. Why would you choose React Native for app development?

This is one of the most commonly asked React Native interview questions for experienced developers. You must consider the following points while answering why React Native is one of the most popular choices:

• It allows developers to build apps faster as there is no excessive recompiling.
• It works independently from the UI and can be used on multiple platforms.
• When combined with CSS and HTML and CSS, it maintains high performance without compromising capability.
• It can be used for multiple platforms and lets developers copy databases from one platform to another.
• You can keep the app running with Hot Reload while implementing new versions and updates.  
• It can merge native components in Objective-C, Swift, and Java. It binds them together for faster and more efficient performance.

Q2. What is the use of InteractionManager in React Native?

The InteractionManager is the native module that allows deferring the execution of a function until an "interaction" has finished. To handle this deferral, you can call InteractionManager.runAfterInteractions(() => {...}). You can also register your own interactions.

InteractionManager has an important role to play as React Native has two threads. The JavaScript UI thread handles drawing updates to the screen. The other thread is used for all tasks, not on the UI thread. During navigation screen animations, the single thread used for making UI updates gets overloaded and drops frames. The use of InteractionManager ensures the execution of functions after these animations have occurred. Thus, ensuring that you don't drop frames on the UI thread.

Q3. What happens when modifying a module that only exports React components in Fast Refresh?

When you modify a module that only exports React components, Fast Refresh updates the code for that particular module. It re-renders your component, allowing you to edit anything in that file, such as event handlers, styles, rendering logic, or effects.

Q4. Enumerate the characteristics of dumb components.

You should thoroughly go through the components, their types, and characters to prepare for React Native interview questions for experienced. The main characteristics of dumb components are as follows:

• There are no dependencies on the rest of the app.
• It is easy to test dumb components. It takes props and returns the UI and does not require any complex logic/ state for data.
• Dumb components mainly focus on the UI, i.e., how things look. You can consider all UI components, including buttons, modals, and inputs, as dumb components.
• These components are dynamic and reusable as they accept props to receive data and the callback function from the parent component.
• They do not include the state except when they have to manipulate the UI itself, not the data.

Q5. What do you understand about HOC in React Native?

HOC, or higher-order component, is an advanced technique for reusing component logic. These components form a pattern that emerges from React's compositional nature and is not a part of the React API. Thus, HOC is a function that takes a component and returns a new one.

Q6. What is the use of a Render Props Pattern?

"Render prop" is a commonly used technique for sharing code between React components. It uses a prop whose value is a function. A render prop component takes a function as a value and returns a React element, and calls it instead of employing its own render logic.

Q7. What is the use of Smart/Container components?

Smart components are capable of fetching, capturing changes, and passing down application data. Several components, including Call Redux, Lifecycle methods, and APIs, are called smart because they are responsible for calling libraries and functionality.

Q8. What is pinning? What is the significance of SSL pinning?

Pinning is an optional mechanism/ technique used on the client-side to improve the security of a service/site that relies on SSL certificates. It allows specifying a cryptographic identity that users need to accept on visiting the site/app.

SSL pinning works by embedding/ pinning trusted certificates to the client during development. Thus, only the requests signed with one of the trusted certificates will be accepted, and self-signed certificates will not be.

Q9. What causes performance issues in React Native?

The primary cause of performance issues in React Native is the fast speed of each thread (Native and JS thread). The performance bottleneck occurs when you pass the components from one thread to another more than required. It is best to keep the passes over the bridge to a minimum.

Another React Native performance issue is memory leakage. It occurs mainly due to unnecessary processes running in the Android app background. Using scrolling lists such as FlatList or VirtualList, instead of ListView is helpful.

Q10. What steps will you take to optimize an application?

This is one of the most commonly asked React Native interview questions for experienced developers. You must consider the following points while answering this question:

• For specific CPU architectures, you can create reduced-sized APK files. It eliminates the requirement of JSCore binaries for supporting multiple architectures.
• You must minimize the application size. Proguard helps reduce the app size by stripping parts of the React Native Java bytecode that aren't used by the app.
• Try compressing images and graphic elements. Using file types such as APNG rather than PNG files can reduce image size.
• You should compress or convert raw JSON data into static object IDs while storing data.
• Optimize native libraries and the number of state operations.
• It is better to use pure and memoized components.
• Using key attributes on list items helps React Native pick which lists to update when rendering a long list of data.
• You must clear all the active timers that can lead to heavy memory leakage issues.

Want more questions for practice? Here’s a comprehensive list of 40+ React Native Interview Questions for tech interview prep.

Technical React Interview Questions for Experienced Developers

Recruiters at technical interviews present senior Java developers with tricky React interview questions. The following list will give you an idea of what type of questions you can be asked in your upcoming React interview.

1. Why would you choose React over Angular?
2. What is the second argument that can be passed to setState? State its purpose.
3. How does a Controlled component differ from an Uncontrolled one in React?
4. Why are API calls made from componentDidMount and not in constructor/componentWillMount?
5. What happens in the initial cycle in React that happens during the first render?
6. Explain the lifecycle of React due to all calls to this.setState.
7. What do you understand about error boundaries in React?
8. What is the role of the new feature of React Memo?
9. Explain the flow in the React-Redux app.
10. What is the significance of middleware redux-thunk?

Recommended Reading: Top 30+ React Interview Questions and Answers.

ReactJS Interview Questions for Experienced Professionals

If you are preparing for a Java developer interview, you should practice these ReactJS interview questions.

1. How is React routing different from conventional routing?
2. How do you style React components?
3. Explain the use of CSS modules in React.
4. What are the main differences between Redux and Flux?
5. Explain the lifecycle methods of components.
6. How would you embed two or more components into one?
7. Differentiate between state and props in context with React Native.
8. How would you update the state of a component in ReactJS?

This completes the list of frequently asked ReactJS and React Native interview questions for experienced. You must also practice the top ReactJS Interview Questions and Answers for better preparation.

FAQs on React Native Interview Questions for Experienced Developers

Q1. What topics are important for React Native interview questions for experienced candidates?

You should thoroughly prepare the following topics to crack the most challenging React Native interview questions for experienced: Components, JSX, Component APIs, React Hooks, and Virtual DOM. Rehearse the most anticipated questions from these topics to nail your interview.

Q2. How do you prepare for React Native interview questions for experienced?

You must begin with basic React concepts and move on to the advanced topics. You must go through React Native interview questions for experienced. Assessing your preparation is crucial, and mock interviews serve as the best opportunity.

Q3. Which IDEs are best for React Native?

IDEs can refactor your code automatically by performing functions such as moving files and extraction of variables. They are quick to perform time-consuming tasks. IDEs require emulators to use the React Native CLI. Xcode and Android Studio are the best IDEs for React Native.

Q4. Which database is used in React Native?

SQLite is a widely used local database for React Native as it is a relational database management system ideal for the storage demands of mobile applications. MongoDB and Realm are also suitable databases for React Native app development.

Q5. What is the average base salary of a React developer in the US?

The average base salary of a React developer in the US is $119,992/year or $61.53/hour. You can also expect additional bonuses and healthcare facilities in addition to the base salary (Source: talent.com).

Gear Up for Your Next Tech Interview

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