Common React interview questions and sample answers
By Indeed Editorial Team
Published 19 May 2022
The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.
What is React?
Common React interview questions and sample answers
Although no two job interviews are alike, there are usually several common themes or topics that React interview questions address. To help you prepare for a technical interview, here are some sample questions that recruiters commonly ask and how to answer them:
1. What makes React different from other methods of application building?
2. Can you explain the difference between virtual DOM and real DOM?
This question is a test of your knowledge of document object models or DOMs. It's a fairly straightforward question that requires a good understanding of these two different types of models. Ideally, try to frame your answer around the core differences between these two models.
Example: 'One of the biggest differences in the context of React is that virtual DOM is often used instead of real DOM. This is because virtual DOM has several benefits over real DOM using the React library. Virtual DOM is much faster when it comes to updates and it uses JSX code for elements that are less memory-intensive. It's also a more cost-effective approach when compared to real DOM because it's less resource-intensive.'
3. What are the stateless components of React?
This question might confuse a few candidates because React is typically known for building interfaces with components that have a state. So the concept of stateless components doesn't usually coincide with React. With that said, there are some integrated stateless components, although they tend to provide a basic function within the code. So to answer this question competently, it's necessary to showcase your knowledge about these components.
Example: 'Although React is typically associated with components that have a state, there are certain functions that can render DOM with pre-existing properties. In React, stateless components are implementable, reusable functions. It doesn't require an internal stage due to the output, which acts as a function compiled of properties.'
Related: 15 signs a job interview went well
4. How familiar are you with Flux?
If you're asked a question that requires you to discuss familiarity or experience with a specific feature, you can apply the STAR method to answer the question comprehensively. The STAR method uses the following structure to answer these types of questions:
Situation: Describe the situation and any challenges you overcame.
Task: Outline your involvement in the task and the resolution.
Action: Discuss the actions taken.
Results: Describe the final results and the role you played in getting there. With the above question, the focus is on an architectural pattern known as Flux. Flux controls derived forms of data in a unidirectional manner to minimise traffic between components and data. React has several key Flux elements that developers often benefit from knowing, so it's a good idea to display your knowledge of this core feature.
Example: 'The Flux pattern uses a unidirectional flow of data actions and movements by allowing data modification from the 'Store', which is a central location in the architecture. When applying any changes, central dispatchers finish the process by sending the updated data to 'Views'. This can change the places where the end-user interacts with data. With Flux, you can only process a single action from the dispatcher's end at any given time, which is useful for data preservation, reliability and integrity.
My previous experience as a React developer involved MVC data flow, but over time issues developed due to a breakdown in the flow of data, which diminished the data's integrity. I then used the Flux architecture to resolve this issue, which resulted in better data reliability throughout the company and efficiencies in data flow. My changes empowered the business leaders to make better decisions through data insights.'
5. What are your thoughts on JSX?
6. Can you describe the lifecycle of React components?
The lifecycle of React is an important component that can add inherent value to businesses using this framework. When interviewing for roles that use React, it can be a good idea to discuss the component lifecycle to highlight your knowledge of this area. It also shows interviewers that you understand its importance to businesses.
Example: 'The lifecycle of React components is an incredibly important part of the framework for a company. Looking at it from a top-down perspective, there are three key features to consider. These are initialising, updating and destruction, which can provide a number of unorthodox approaches and uses. For example, at the initialising phase, there are actions such as getInitialState() or getDefaultProps() which are relatively abstract and very useful.'
What to expect in a React interview
If you're preparing for a React interview, there are several things to expect. To make sure you're ready for the interview, consider preparing for the following:
Interview questions: Most interviews contain verbal questions for you to answer, just like the ones outlined in this article. They could focus on several topics, such as behaviours, experience or technical skills. For React interviews, questions are most likely to focus on technical areas.
Assignments: Some interviewers ask candidates to take home an assignment to gauge their competency in React. You usually receive this after the initial interview to further determine your eligibility for the role.
Multi-structured interviews: You can expect to have more than one interview, starting with a simple screening interview to match your skills to the role. From here, a second and even third interview may be necessary to further assess your aptitude to see if you're suitable for the role.
Please note that none of the companies, institutions or organisations mentioned in this article are affiliated with Indeed.
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