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Top 30 Advanced ReactJS Interview Questions and Answers

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React, also known as React.js or ReactJS, is a front-end, open-source JavaScript library used to create user interfaces through the use of UI components. If you are a Java programmer, you can expect advanced ReactJS interview questions in your front-end engineer interview.

To understand your experience with various Java tools and frameworks, FAANG+ companies typically test your knowledge of Java application tools and Microservices, including ReactJS. To ace your technical interview, it is critical to know the answers to frequently asked advanced ReactJS interview questions.

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This piece will look at some popular advanced ReactJS interview questions asked in technical interviews at FAANG+ companies. 

Here’s what we’ll cover in this article:

  • Popular Advanced ReactJS Interview Questions and Answers
  • Sample ReactJS Interview Questions for Practice
  • FAQs on ReactJS Interview Questions

Popular Advanced ReactJS Interview Questions and Answers

Q1. What are some key benefits of using ReactJS?

This is a common advanced ReactJS interview question asked in technical interviews. Some key benefits of using ReactJS include: 

  • ReactJS is the best framework for front-end development in Java as it is packed with a host of features. 
  • ReactJS uses a Virtual DOM, thereby enhancing the performance of applications built using the framework. 
  • React employs a component-based architecture and allows components to be reused with great ease. 
  • React has a vast list of tools and libraries, providing impressive depth and flexibility. 

Q2. What is the Virtual DOM in React?

Virtual DOM is a feature through which a virtual version of the real DOM is placed in the memory. Using the ReactDOM library, the virtual and real DOMs are synced whenever required. 

Q3. Which are the different Lifecycle phases in ReactJS?

This is another important advanced ReactJS interview question asked in technical interviews. Components in ReactJS fundamentally go through three Lifecycle Phases.

  • Unmounting
  • Mounting
  • Updating

Q4. Which are the various Lifecycle Methods in the Mounting Lifecycle Phase?

The various methods in the mounting Lifecycle Phase include:

  • Render
  • ComponentWillMount
  • ComponentDidMount

Q5. Which are the different Lifecycle methods in the Updating Phase?

The lifecycle methods in the Updating Phase include:

  • ComponentWillReceiveProps
  • Render
  • ComponentDidUpdate
  • ShouldComponentUpdate
  • ComponentWillUpdate

Q6. What is an Event in ReactJS?

Events are actions that are performed by the user or computer. Actions such as clicking and pressing keys are examples of Events in ReactJS. Unlike in HTML, where events are in lowercase, events in React are in CamelCase. 

Q7. What are some prime features of the ReactJS framework?

This again is a frequently asked ReactJS interview question asked in technical interviews. 

The prime features of the ReactJS framework include:

  • ReactJs allows for Data Binding, where developers can choose what elements users can access and what elements are hidden. The security of applications created is also foolproof because of this feature.
  • ReactJS has a unidirectional data flow.
  • ReactJs employs Virtual DOM instead of RealDOM.
  • React mainly uses Server-side rendering.

Q8. What is Redux?

Redux is a popularly-used library for front-end development. It is loaded with a spate of features that help accomplish advanced front-end tasks using UI components. Applications built using Redux are easy to test and can seamlessly run on multiple framework environments. 

Q9. What are some advantages of using Flux?

Flux offers a bunch of advantages, the most important ones being:

  • It ensures uniformity of code execution, thereby preventing Runtime errors. 
  • It helps to perform updates more effectively through unidirectional data flow, thereby improving the efficiency of the application. 

Q10. What are some functions that can be performed using HOC?

Using HOC, you can -

  • Render Hijacking
  • Manipulate and Reuse code
  • Manipulate Props

Take a look at some ReactJS Interview Questions and Answers here.

Sample Advanced ReactJS Interview Questions for Practice

In this section, we’ll look at some additional ReactJS interview questions that you can practice for your upcoming interview. 

  1. Why do we use Keys in ReactJS lists?
  2. How can the transversal of lists be achieved in ReactJS?
  3. What do you understand about components in React?
  4. Explain the two types of Components in ReactJS?
  5. What are Synthetic events in React?
  6. What are Pure Components in ReactJS?
  7. What are some important features of Redux?
  8. What do you understand about Flux in React?
  9. Why are Routers used in ReactJS?
  10. What are some disadvantages associated with the ReactJS framework?
  11. Why can’t browsers read JSX? How can browsers be made to read JSX?
  12. What do you understand about Higher-Order Components in ReactJS?
  13. What do you understand by References in ReactJS?
  14. What are Props in ReactJS?
  15. How do you modularize code in the ReactJS framework?
  16. What is the use of Webpack in React?
  17. What is Babel in ReactJS?
  18. What is Prop-drilling in ReactJS?
  19. What are Error boundaries in ReactJS?
  20. What do you understand about the Strict mode in React?

These above advanced ReactJS interview questions will help you understand the type of questions asked in your Java developer interview, especially if you are a front-end developer. 

FAQs on Advanced ReactJS Interview Questions

Q1. Do you need to be good with ReactJS for backend developer roles?

As ReactJs is primarily an open-source front-end framework used for building interface applications, you don’t need to know your way around ReactJS if you’re a backend developer.

Q2. When should you expect advanced ReactJS interview questions in Java developer interviews?

You can expect advanced ReactJS interview questions during the coding and systems design rounds if you’re appearing for a software engineering interview.

Q3. What main concepts should you prepare to answer advanced ReactJS interview questions?

Advanced ReactJS interview questions are mostly around Redux, Components, Flux, Synthetic Events, Virtual DOMs, and Security. 

Q4. What is Lazy Loading in ReactJS?

Lazy Loading is a feature where buckets of code are bundled together and deployed simultaneously after each block of code is executed. 

Q5. What is the use of JSX in React?

JSX in React is a JavaScript XML file that helps write HTML code in the React framework. 

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