ReactJS is among the top-rated technology in web development. If you’re planning an interview for a job or want to brush up on your skills, it’s crucial to know the basic principles that underlie this robust JavaScript library. This article will cover the top seven ReactJS interview questions, with clear solutions to help you get prepared.

1. What is ReactJS and why is it popular?

ReactJS is an front-end JavaScript library created by Facebook to build user interfaces, particularly single-page apps. It lets developers create reuseable UI components, which makes the codebase more manageable and expand. One of the primary factors behind its popularity is the speed due to the usage for the virtual DOM that updates the interface in a timely manner without reloading the entire page.

2. What are the main features of ReactJS?

React has a number of key features that help the application unique. Its first feature is JSX an extension to syntax that allows you to create HTML-like code directly in JavaScript which improves comprehension. The second is that React uses a structure based on components which means that the UI is broken down into smaller pieces that can be reused. Thirdly, React uses a virtual DOM to accelerate rendering. Additionally, the one-way data flow makes the application logic more reliable and easier to identify.

3. How do functional components differ from class components?

Functional components are less complicated and built on basic JavaScript functions. They are generally easier to comprehend and test. React introduced Hooks to enable functional components to handle states and side effects which was previously a requirement for classes to manage them. Class components are, however make use of ES6 classes, and are equipped with lifecycle techniques. Although both are able to accomplish similar tasks, the majority of modern React applications are now using functional components that have hooks due to their simpler and simpler syntax.

4. What is the virtual DOM and how does it work?

Virtual DOMs are a copy in memory of the real DOM. If the condition of a component is changed, React first updates the virtual DOM, instead of the actual DOM. Then, it compares the updated Version of the DOM to the previous version and determines the change. Only those modifications are incorporated into the actual DOM. This process, referred to by the term “reconciliation,” ensures optimal performance as well as a more pleasant user experience.

5. What are React Hooks and why are they important?

Hooks are functions that were built-in and introduced within React Version 16.8. They permit developers to utilize state as well as other React features within functional components that were previously only available as class components. The most popular hooks are useState to manage state, useEffect for managing unwanted effects such as fetching data and useContext to access context information with no prop drilling. Hooks can simplify code and promote the usage functions in the modern React development.

6. What is the difference between props and state in React?

Props and state can both be utilized to manage information in React However, they serve different functions. Props, a short form in the sense of “properties,” are read-only and pass from an element that is a parent to a child component. They can be used to configure or modify components. State however is a local information storage that is specific to a particular component. It is able to alter over time, typically as a result of user interaction and influences how the component performs or appears.

7. What is the purpose of the useEffect hook in React?

The hook used by useEffect is employed to control the side effects of functional components. These side effects could include things such as fetching data from an API or changing the title of the document or establishing event listeners. The hook will run when the component renders, and can be programmed to run only when certain values alter. This prevents unnecessary rendering and makes the component running efficiently. In short, using effect replaces lifecycle methods such as componentDidMount or componentDidUpdate in classes of components.

Conclusion

The preparation for an ReactJS interview is more than memorizing questions. It’s about knowing the fundamentals of ReactJS Training and also being capable of explaining them in a clear manner. The top seven questions in this list touch on the most frequently discussed issues in interviews. They offer solid foundations for anyone seeking to impress recruiters and hiring managers.

As React continues to grow by adding new features like hooks or optimization techniques for performance will make you stand out in the job market. If you’re just beginning to learn about React or are aiming for an executive position, understanding the fundamentals of React will be a major step in your growth journey. You can explore further with Digital Marketing & Programming Courses.