React Native Interview Guide

React Native Important Interview Questions

Every developer has to go through the interview process once, twice or many times in their career. And as many times as we give it, every time there’s a chill that runs down the spine when you have to give an interview especially when the job matters to you.

One thing that helps is being prepared for the interview. Preparation makes you confident, powerful and relaxed (to an extent).

I, like any other developer, do go through the same round of interviews, job hunting, even after getting a good job interviewing again to land a better job.

React Native and Android are my fields of coding and I give interviews in those fields.

Here I am, sharing the questions that I have come through and the questions that tend to be frequently asked in interviews which’ll help you prepare well beforehand any interview. I would like to believe I have covered all topics/questions and referring to this should suffice to a greater extent. If I have missed out any topics or important questions that are frequently please let me know Bhavna V Haritsa and I shall give you a shoutout in the blog.

Well, I don’t have the answers for now. I will make a detailed doc with the answers, explanations and flowcharts (if needed) but here we are, with the questions alone.

Letssss go!!

Basic questions:

1. What is React Native? (Yes, this is still asked)
2. Difference between React and React Native.
3. Advantages of React Native.
4. Disadvantages of React Native.
5. What are the core components of React Native?
6. What are the main performance issues in React Native?

Virtual DOM:

1. How does React Native run in the background?
2. What is Virtual DOM and how does it work in the background?
3. What is the process of reconciliation in React Native?
4. How is virtual DOM better compared to Real DOM and Shadow DOM?
5. What are the threads in React Native?

Styling:

1. What are the different ways to style your component in React Native?
2. How to handle element size according to different screens in React Native?
3. Flexbox in browser vs Flexbox in React Native.
4. What does Stylesheet.create() function do?
5. What are the naming conventions of style properties?

Reference Article: https://www.bigbinary.com/books/learn-react-native/styling-in-react-native

View Components in React Native:

1. What are touchable components in React Native?
2. What is Flexbox in React Native?
3. What are the properties of Flexbox in React Native?
4. How does alignItems and justifyContent work when Flex direction is row?
5. What is the difference between alignItems and alignContent?
6. What does Flexwrap mean?
7. What are pure components in React Native?
8. What is meant by display flex?
9. What is KeyboardAvoidingView?
10. What is VirtualizedList?
11. Listview in React Native.
12. What is the difference between an element and a component?
13. Are all components used in React used in React Native as well?

Flatlist:

1. Flatlist in React Native and its advantages over listview.
2. What are the key features of Flatlist?
3. Do we need a scrollview while using Flatlist?
4. How to re-render a flatlist?
5. Flastlist advantages over scrollview.
6. Can a flatlist render data horizontally?
7. When would you use a ScrollView over a Flatlist?
8. What does ItemSeparatorComponent do in React Native?

Reference Article: https://www.knowledgehut.com/blog/web-development/react-native-flatlist

States and Props:

1. What are states?
2. What are props?
3. Differences between state and props.
4. What are default props in React Native and why are they necessary?
5. What are props drilling?
6. How can we avoid props drilling in React Native?
7. How do you update the state of a component (class and functional)?
8. How do you pass props between components?
9. What is setNative Props?

Components in React Native:

1. What are the different ways of writing a component in React Native?
2. Difference between class based and functional based components.
3. What are Stateful and Stateless components?
4. What are controlled and uncontrolled components?

Class components in React Native:

1. What are class components in React Native?
2. Explain the lifecycle of a class component.
3. For what reason, the render() method is used inside a class component?
4. When is the constructor method called inside the class component?
5. In which case would you prefer a class component over a functional component?

Functional components in React Native:

1. What are functional components in React Native?
2. Do functional components have a lifecycle on their own?
3. How do functional components manage lifecycle changes happening in class components?
4. What are pure functional components?
5. Will react hooks work in class components?

Hooks:

1. What are hooks?
2. Why were hooks brought up in React Native?
3. How do hooks replace the lifecycle methods of class components?
4. Explain useState, useEffect, useCallback, useMemo and useRef.
5. Difference between useEffect and useLayoutEffect.
6. What are the rules while using hooks in React Native?
7. What are custom hooks and how can we create them?
8. How can you update the current state value based on previous state value in React hooks?
9. What are the differences in using hooks and state management in class components in React Native?

Databases:

1. What type of database works best in React Native?
2. Explain AsyncStorage in Rea​​​ct Native.
3. How can sensitive data be stored securely in React Native?

Networking:

1. What are bridges in React Native? Why are they used?
2. Describe networking in React Native.
3. How to make AJAX network calls in React Native?
4. What is the use of the XHR module in React Native?

Optimization:

1. How can you optimize the performance of images?
2. How to optimize a large list in Flatlist?
3. How can you avoid React Native multi-threading issues?
4. Discuss ways to reduce memory leaks in apps?
5. How can you cache React Native images?

Redux:

1. What is meant by Redux?
2. What is meant by Flux?
3. What is the difference between Redux and Flux?
4. Core principles of Redux?
5. Difference between mapStateToProps() and mapDispatchToProps
6. What are constants?
7. What are reducers?
8. Explain data flow in a typical application made with React Native and Redux.
9. What is meant by store in Redux?
10. Name all the Redux store methods.
11. How to set the initial state in Redux?
12. What are the workflow features in Redux?
13. What are Redux forms?
14. What do you understand about the Redux Saga?
15. Name all Redux store methods.
16. What does “store” mean in Redux?

Others:

1. What is HOC in React Native?
2. Explain timers in React Native.
3. What is meant by refs in React Native?
4. What is a Gesture Responder?
5. What does an interaction manager do in React Native?
6. Difference between live reloading and hot reloading.
7. What is the use of arrow function in React Native?
8. Why are keys used in React Native?
9. What is Fabric?
10. How can you write tests in React Native?
11. How do you persist data in React Native?

Reference Article: https://blog.codemagic.io/improve-react-native-app-performance/

I hope you found them useful. All the best :)

Bhavna Haritsa.