React js Interview Questions

React js interview questions


This comprehensive guide has three sets of important React js Questions and answers: Beginners, Intermediate and Advanced.

Read, learn, practice and prepare yourself with these sure-shot React js interview questions to crack your next interview for a React js developer job.

Introduction - React js Interview Questions and Answers

We have compiled the top React js interview questions and answers for you to prepare for your next interview. We have divided the questions into three categories based on experience.

React jsInterview Questions for Beginners
Intermediate React jsInterview Questions
Advanced React jsInterview Questions

We have selected the most asked React js questions in any interview. Each of these questions represents some core insights on the React js Programming language.

But first let’s discuss – Why is React js one one of the top programming languages? Why is there high demand for React js developers? What makes React js Development a competitive job?

React js provides a great advantage because it allows you to reuse codes, which boosts your company’s efficiency. A user-friendly framework for web development is React js. There are various characteristics, including user-friendliness, adaptable coding environments, and SEO best practices. Additionally, it offers HTML rendering, one of the most crucial aspects that makes it user-friendly and increases developer productivity. Using Node, React js can render on the server. It implies that with React Native, developers may create native apps. Instead of using challenging UI components combined into one, it uses a single component to develop an app.

With more developers working on it, React js fought jQuery to overtake it as the most widely used and popular web framework in 2021. Because of its scalable and low-maintenance system, the majority of firms, like Netflix, Dropbox, Facebook, BBC, and Yahoo Mail, now favour React framework for their development activities. It connects with various technologies and is straightforward, simple to learn, and versatile. Due to all these advantages, there is a high demand on the job market for React specialists. Naturally, this competition raises wages all throughout the world. This guide will assist you in determining the appropriate cost of hiring a React developer for your unique project.

The learning curve for React js programming is not as high as it is for other frameworks. React is a simple, light-weight Js framework that just works with the view layer, making it adaptable and intuitive. Therefore, developers simply need a foundational understanding of traditional JavaScript to get started. Due to the simplicity and clarity of the situation, React js has emerged as a viable solution for enterprise development. The general process of writing components is made easier by react. It permits HTML quoting and guarantees simple display of subcomponents. A JavaScript syntactic extension called JSX makes creating your own components much simpler. As a result, fresh React js developers also immediately began adopting this framework to create online applications.

React js Interview Questions for Beginners

1. What is React?

React is a JavaScript front-end toolkit that primarily uses the component-based method to create user interface (UI) components for single page applications. In mobile and online apps, it is also used to manage the view layer. React is also essential for creating interactive mobile and online user interfaces. Jordan Walke was the one who conceived of it and worked on its development; it debuted in 2011 in the Facebook newsfeed.

2. Name the important features of React

Here are important features of React.

Allows you to use 3rd party libraries.


Faster Development.

Simplicity and Composable.

Fully supported by Facebook.

Code Stability with One-directional data binding.

React Component.

3. What are the life Cycles of React js?

State/Property Updates

4. What is JSX?

It is basically a new JavaScript dialect that just incorporates HTML templates into the JavaScript code. There is a requirement for this integration because the browser cannot comprehend the code easily. Tools like WebPack or Babel are typically taken into account for this process. In the current environment, it has become a very well-liked strategy among developers.

5. How is React JS framework different as compared to others?

React js is fundamentally different from a sizable portion of other JavaScript structures in that it is a constrained library that creates UI components. One typical illustration is the way AngularJS constructs apps by merely expanding HTML content and injecting various developments like controllers at runtime. Because of this, AngularJS is very adamant about the more important engineering of your application.

6. Does React JS use HTML?

No, It uses JSX which is similar to HTML.

7. What is the higher-order component?

A high order component in React js is characterised as the function that primarily collects components and returns a new component. These parts are the patterns that were drawn from the compositional structure of React. This component’s use in React as reusable component logic is one of its key features. The greatest technique to share behaviour amongst various React components is provided by it.

8. What is Redux in React?

In today’s expanding world, it is one of the most used libraries for front-end programming. It is described as the predictable state container that was primarily created for JavaScript apps and is also used to manage an application’s whole state. Redux is extremely compact and independent. It creates apps that are simple to test and deploy in many settings. Redux is extremely compact and independent.

9. What are the popular animation packages in the React ecosystem?

Popular animation package in React ecosystem are

React Motion
React Transition Group

10. Why do we need a Router in React?

A Router is especially useful for defining and creating multiple routes. When you enter a URL that matches a path of any route defined within the router, you will be redirected to that route. Essentially, you will avoid all other routes in order to reach the one you require.

Intermediate React js Interview Questions

As a React js developer, with experience you will be able to answer React js interview questions for freshers with much ease. In this section we have collected some React js tricky interview questions for you. This section will help you with the exact kind of Intermediate React js Interview Questions that you may face in your job hunt.

1. What do you know about Flux in React?

Flux is a simple illustration that aids in the maintenance of a unidirectional data stream. Its purpose is to control the unique fragments of constructed data so that they can interact with that data without causing problems. Flux configuration is insignificant; it is not unique to React applications and is not required to collect one. Flux is a simple concept, but you must demonstrate a thorough understanding of its application.

2. What are refs in React? When to use them?

Refs are used for storing the reference of an element or component returned by the component render() configuration function. In most cases, they should be avoided although there are some instances when using them is useful, such as:

Managing focus, text selection, or media playback.

Triggering imperative animations.

Triggering imperative animations.

3. What is Context?

Context allows data to be passed through the component tree without having to manually pass props down at each level.This means you can nest items as deep as you want.It is primarily used when multiple components at different nesting levels require access to the same data.

4. What’s the difference between an Element and a Component in React?

A React element is an object that represents some UI.It essentially describes what you want to see on the screen.In contrast, a React component is a function or class that accepts input and returns a React element.This is also a common interview question about React js.

5. What is the use of the arrow function in React?

An Arrow function eliminates bugs brought by this entirely because it enables you to anticipate how bugs would behave when supplied as callbacks.

6. What is the difference between DOM and virtual DOM in React js?

An abstraction of structured code is called DOM, or Document Object Model (HTML).HTML code and DOM are related because HTML elements are referred to as DOM nodes.It establishes a structure that allows users to adjust the structure’s content however they see fit (create, edit, alter, modify etc.).DOM is an in-memory representation of this content, and HTML is essentially a text.A lightweight duplicate of DOM objects is represented by virtual DOM.React js makes use of and offers it without charge.

7. How do you tell React to build in Production mode and what will it do?

Normally, you would set NODE ENV to production using Webpack’s DefinePlugin function.Things like propType validation and additional warnings would be removed.It would be a good idea to minify your code as well because React will drastically reduce the size of your bundle by removing development-only code and comments using Uglify’s dead-code reduction feature.

Advanced Magento developer Interview Questions

This section contains some advanced interview questions on HTML. This section also explores a few React js coding Interview questions. You may practice the common React js Programs which the interviewer often asks.

1. Explain mixing or higher order components (HOC) in React.

HOC are functions in React that accept and return components.It essentially recycles component logic.Having said that, you should be aware that HOC isn’t really a component of the React API.They are functions that perform a loop across all elements in an array.When responding to React js questions, have that in mind.

2. What are synthetic events in React?

Synthetic events should be mentioned when discussing React js interview questions and answers.They function as a cross-browser wrapper around the native event of the browser, merging the functionality of several browsers into a single API.They serve to guarantee that the events display uniform attributes across browsers.

3. What can you do with HOC?

You can use HOC for:

  • Code reuse, logic and bootstrap abstraction
  • Render hijacking
  • State abstraction and manipulation
  • Props manipulation
  • 4. What is Redux Thunk used for?

    Speaking of React js Redux, you ought to be familiar with Redux Thunk, which is a programming language for creating action producers that return functions rather than actual actions.

    Additionally, if a specific need is met, it can be used to postpone the dispatch of an action.This enables us to manage the dispatching of activities in an asynchronous manner.The storage methods dispatch and getState are passed as parameters to the inner procedure. .


    We hope these React js Interview questions and answers will be of great assistance to you throughout the process, whether you’re a developer getting ready for an interview or a hiring manager looking for the best applicant.

    Remember that the hiring process involves more than just technical expertise. To ensure that you land a high paying React js Developer job, both previous experience and soft skills are crucial.

    A lot of the React js interview questions are open-ended, so keep that in mind. Interviewers are interested in your reasoning, not just the answer you memorised. Always be ready for follow-up questions regarding how you arrived at your answer. Describe your thought process.

    Good luck with your upcoming React js interview! You can go through our React js developers jobs here.