25 Most Important Interview Questions and Their Correct Answers for React Js in 2023

Are you looking for questions to ask a potential React developer during an interview? If so, it is important to ask questions that are pertinent to the job and will help you determine if the candidate is a good fit. Some common questions that may be beneficial to ask include:

  • What experience do you have with React JS?
  • How comfortable are you with writing and testing React components?
  • What challenges have you faced when working with React?
  • Describe a project you have worked on that involved React.
  • Can you provide an example of a React application you have built?
  • How do you handle state management in React?
  • How familiar are you with React best practices?
  • How have you incorporated React into existing projects?
  • What have you done to optimise performance in React applications?
  • What experience do you have working with React Native?

Try to find the answers to these questions. Maintain your course of study.

Introduction

React is a JavaScript library framework that enables developers to create lightweight, responsive, and extensible web applications. Developed by Jordan Walke, a software engineer at Facebook, the framework can be easily customised and offers a high degree of efficiency. React was first used in 2011 on the news feed of Facebook, and in 2012, Instagram adopted the framework.

React is quickly becoming one of the most popular front-end frameworks among developers due to its ease of use when creating web applications. This has caused an increase in the number of businesses leveraging React’s technology, creating a demand for talented and experienced React JS professionals. If businesses want to stay competitive, they should look to employ individuals with the requisite expertise in the React JS framework.

Despite the abundance of competition for React JS developers, it can still be challenging to source and recruit the most qualified candidates. To ensure that you are bringing in the top-tier engineers, it is critical to have a well-thought-out recruitment strategy in place. Furthermore, no recruitment process can be considered complete without a rigorous selection of interview questions.

No matter your profession, whether you are a recruiter or a developer, having a familiarity with the 25 most commonly asked React JS interview questions and their answers in 2023 is essential. Acquiring this knowledge will ensure that you are well-prepared for any potential interview scenarios.

Here are the answers to the top 25 React JS interview questions.

  1. Just what does “JSX” stand for?

    The initials JSX stand for “JavaScript XML.” To fully realise JavaScript’s capabilities, React employs the language’s standard extension, JSX.

    JSX provides a basic syntax incorporating elements of both HTML and JavaScript, allowing for the creation of human-readable HTML files and enhancing the productivity of the program.
  2. Can JSX files be opened in browsers?

    It is not possible for browsers to read JSX files as-is; they are only able to interpret JavaScript objects. To enable browsers to understand a JSX file, it must be converted into a JavaScript object through the use of JSX transformers. Put simply, JSX transformers are necessary in order for a browser to be able to interpret a JSX file.
  3. Just what is the deal with React’s Flux concept?

    Facebook routinely utilises the concept of Flux architecture for the development of web applications that are distributed to users’ local computing devices. Flux works in conjunction with React and the concept of single-directional data flow; however, it is neither a library nor a framework.
  4. Give An Explanation Of What You Mean By Redux.

    Redux is an open-source JavaScript library designed to create user interfaces. It functions as a container that stores data and settings for your programs, and provides a structure for efficiently managing the state of those programs in a variety of environments. It is well-suited for applications that require frequent updates and modifications, and offers the potential for scalability and long-term maintainability.
  5. Can you explain Redux’s “Store” function?

    Redux’s ‘Store’ feature enables programmers to store the state of their entire application in a centralised location. This allows them to benefit from consolidating the application’s various components into one repository and to register for automatic updates to the store. Additionally, the consolidated state tree makes version tracking and debugging processes simpler and more efficient.
  6. In Redux, what exactly is an action?

    Redux is a technique of state management which involves the usage of action objects to exchange data between an application and its store. Action objects typically contain the type of action to be performed and any associated data. The store only receives data which has been generated through user activities.
  7. What are some of React’s most notable features?

    The key aspects of React are as follows:
    1. Time-saving
    2. Provides a shorter time to market
    3. Offers Convenience for Future Work
    4. Full backing from Meta
    5. Provides code consistency via unidirectional data binding
    6. Provide a wide variety of features
  8. Exactly what is Virtual DOM, and how does it function?

    The Virtual DOM is a lightweight JavaScript object that acts as a carbon copy of the original Document Object Model (DOM). The DOM is a data structure comprised of a hierarchical arrangement of nodes that store information regarding elements, their attributes, and their content in the form of objects with their own distinct properties.

    When employing React JS, the render() method is tasked with constructing a node tree from the React components. During the development process, the tree is updated and modified according to the data model which are impacted by different user and system interactions.

    The steps required to use the virtual DOM are as follows:
    1. Step 1: As soon as there are changes to the underlying data, the complete UI is re-rendered in Virtual DOM form.
    2. Step 2: The system determines how much of a change there was between the old and new DOM representation.
    3. Step 3: After the computations are complete, the actual DOM is modified to reflect the new data.
  9. Explain the distinction between the Real DOM and the Virtual DOM.

    The Distinction Between Physical and Digital DOM
    1. Modifying The Document Object Model: True DOM may put a dent on your budget. Conversely, the cost of a virtual DOM is little.
    2. Material Improvements: The true DOM generates a new DOM whenever an element is modified. In instead of updating the JSX, Virtual DOM updates the DOM.
    3. Loss Of Long-Term Memory: As opposed to the memory-free virtual DOM, the actual DOM requires a large amount of RAM.
    4. The Rate Of Change: It takes a while for the actual DOM to be updated. Speedier updates are available in the virtual DOM.
    5. Changes To Html: While the virtual DOM cannot directly modify HTML, the actual DOM can.
  10. How do React components go through their lifecycle?

    The React component lifecycle methods are as follows:
    1. componentDidMount(): Runs in the client once the first rendering is complete.
    2. componentDidUpdate(): Called just after DOM rendering is complete.
    3. componentWillMount(): Runs on both the client and the server just before rendering begins.
    4. componentWillReceiveProps(): Called before to the next render invocation once the parent class has received props.
    5. componentWillUnmount(): Purges the heap and is invoked just after the DOM unmounts the component.
    6. componentWillUpdate(): Executed just before the DOM is rendered.
    7. shouldComponentUpdate(): The result will be true or false. Though it normally returns false, if the update is necessary, it must be changed to return true.
  11. Why should I use a React router instead of a regular one?

    Here is how a React router differs from a regular one:
    1. Adaptations to the Web address: The conventional method of routing involves sending an HTTP request to a server in order to get the relevant HTML page.
    2. Navigation: In conventional routing, users are required to navigate through multiple webpages in order to gain access to each distinct view or perspective. However, with React routing, visitors to a website are given the impression that they are navigating from page to page, when in reality they are remaining on the same page. This efficient methodology of routing offers a user-friendly and seamless experience for visitors.
    3. Pages: Unlike conventional routing, in which each view corresponds to the same file, React routing uses a separate file for each view.
  12. When comparing two teams, what role do the “props” play vs the “stats”?

    The distinction between ‘advantages’ and’statistics’ is as follows:
    1. Inside child components, changes to props are permitted but changes to the state are not.
    2. The state, but not the props, may be used to modify the internals of the component.
    3. When a parent component is using the state, the value cannot be modified.
  13. Can you explain the difference between Redux and Flux?

    The distinction between Redux and Flux is as follows:
    1. Dispatcher: The redux framework does not provide a dispatcher. Flux, on the other hand, uses a centralised dispatcher.
    2. Retail Outlets: If you’re familiar with flux, you know that it has several stores, whereas redux just has one.
    3. State: In flux, state can be changed, but in redux, it cannot.
    4. Store: The store in this context is dynamic due to its inclusion of state and transition logic. This contrasts with Redux which separates the storage and updating mechanisms into separate components.
    5. Format Of Store: All currently open shops are isolated and have no depth. As opposed to this, redux does not suffer from this problem.
  14. Can you comment on the claim that “In React, everything is a component?”

    The user interface (UI) of a React application is constructed by breaking it down into smaller, independent components. This allows for a more organised approach, since each component can be developed and tested separately, and then integrated into the larger application. This can help to ensure that the UI is robust and efficient, offering an optimal user experience.

    In React, each component is shown separately from the others. Therefore, the UI of the app is unaffected by the rendering of a single component.
  15. Please explain React’s modular, component-based design

    React components form the foundation from which user interfaces for applications are constructed. Once the component-based system is established, each part can be repurposed and works independently of the other components. This implies that the application can be presented quickly and without the need for additional UI components.
  16. What is the procedure for rendering in React JS?

    Each component in React JS needs rendering to function properly.

    After invoking the render() method, a Document Object Model (DOM) element is produced which represents the component. Web developers can effectively render a multitude of HTML elements at once by collecting the tags and then utilising the render function on the objects.
  17. In React, what exactly are states?

    It is commonplace to consider states in ReactJS as a source of data or objects that manage various aspects, such as the behaviour and rendering of components. Thanks to states, creating dynamic and interactive components is straightforward and effortless.
  18. Can you explain what a React higher-order component is?

    In order to take advantage of the benefits of code reuse and abstraction layers, many React developers opt to use Higher-Order Components (HOCs). HOCs are a common pattern within the React API and provide developers with a powerful tool to quickly and efficiently implement the logic of component reuse.

    The utilisation of Higher Order Components (HOCs) facilitates the sharing of behaviours among all React components, making the process simple and straightforward. This, in turn, increases the effectiveness and usability of the entire application.
  19. Is it possible to explain the ‘create-react-app’ React command in detail?

    React’s create-react-app command provides a no-frills command-line interface (CLI) for developing React apps.

    By using the CLI, users may focus on the application’s code rather than configuring ancillary tools.
  20. Describe some of the advantages of running create-react-app.

    Advantages of React’s create-react-app command
    1. Integration of Flow Statements, ES6, and JSX
    2. Auto-prefixed CSS is already developed and available.
    3. Modules of rapid-fire interactivity for examination
    4. Web-based debugging tools for real-time development
    5. Scripts for managing JSS, CSS, and other file types
  21. What exactly are React’s “synthetic events?”

    Synthetic events are objects in React that serve as cross-browser wrappers for native events. This approach ensures that the application programming interface (API) is compatible with different web browsers and that all of the necessary attributes are included in the event.
  22. When talking about React, what exactly do you mean by “stateful components?”

    In computing, “stateful components” are those that can detect and store changes.
  23. In React, what exactly are “refs”?

    References in React can be referred to as “Refs”. Refs provide a way to save a reference to a specific React element or component. The render function can be used to return this reference.

    The most common contexts for using a reference are as follows:
    1. As a means to set in motion necessary animations
    2. In order to integrate external DOM libraries
    3. With the aim of regulating attention and implementing media application
  24. In React, what exactly are “controlled components”?

    React’s controlled components are the ones that can store and retrieve their own state. The parent component owns all of the data, which can be accessed through properties. Controlled components rely on callbacks to inform developers about any potential changes in the state.
  25. Does React have any restrictions?

    React has numerous restrictions, such as:
    1. It’s not really a framework, but more of a library.
    2. It would take quite some time to go through everything in the library and understand it.
    3. This is quite confusing.
    4. This is especially true when using inline templating and JSX, both of which make programming more challenging.

Ultimately, however

Prior to responding to any questions related to React and JavaScript, it is highly recommended to gain a thorough understanding of the fundamentals of both technologies. To ensure optimal comprehension of the content, one should take the time to read extensively on the subject in order to reinforce their knowledge.

As a recruiter, it is essential to maintain a comprehensive and effective interview process regardless of the recruiting method utilised. In order to ensure that the best possible candidates are hired, it is paramount that the interview panel is well-informed and able to ask both fundamental and advanced questions related to React JS.

If you’re having trouble recruiting React JS engineers and can’t seem to settle on a solid plan, give Works a go.

When it comes to recruiting, Works is well-equipped to satisfy the staffing needs of organisations of all sizes. With Works, businesses can rapidly find and hire highly qualified React JS developers in a period of only three to five business days.

FAQs

Can you recommend any questions I should ask my React developer?

Some common topics for interviews with React JS are listed below.

  • In depth, what is ReactJS?
  • Where does ReactJS find the majority of its applications?
  • Which comes first, React or the back end?
  • Why does React use JSX?
  • Can you tell me what JSX stands for in its entirety?
  • Do HTML and CSS even matter for React?

The question is, “What should I ask in a React JS interview?”

Mix in some non-technical inquiries with the technical ones.

Questions for a Technical Interview in React JS

  • Virtual DOM: what is it?
  • The question is, “How do you make a React app?”
  • In React, what exactly is an event?

Questions for a React JS interview that aren’t technical:

  • Exactly where do you fall short, exactly what are your flaws
  • To what extent do your qualifications justify an employment offer?
  • You must have a good reason for quitting your previous work.

Give me the lowdown on React JS, please.

The React JavaScript library is an open-source implementation of the widely-used front-end web development technology. This library is designed to enable developers to quickly and easily create user interfaces (UIs) by way of intuitive, ready-made UI components. A consortium of independent software developers and IT companies provide ongoing support and maintenance for the React library.

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