The Top Most asked react js interview questions

The React course will show you how to make apps for your phone, computer, and other devices. Frequently asked react js interview questions may be found on this page.

1.What is the function of the 'prop-types' library?

ANS:The 'Prop-types' package enables you to do runtime type verification on props and other related objects in a recent application.

2.Define the terms mounting and demounting.

ANS:Mounting refers to the procedure of connecting the element to the DCOM. The demounting procedure refers to the process of removing the element from the DCOM.

3.Can you change the values of the props?

ANS:Because props are immutable, it is not feasible to alter their value.

4.Explain the concept of'restructuring.'

ANS:Restructuring is the process of extracting array objects. When the operation is finished, you may split each item into its own variable.

5.Is it possible to change props in React?

ANS:Because properties are read-only, you can't update them in react js. Furthermore, you cannot edit properties passed down from parent to kid.

6.Is it possible to re-render a component without utilising the setState() function?

ANS:You can re-render any component by using the forceUpdate() function.

7.Define the phrase "reconciliation."

ANS:When a component's state or props change, rest will compare the rendered element to previously rendered DOM and, if necessary, update the real DOM. This is referred to as reconciliation.

8.In the parsing, how can you share an element?

ANS:We can share the data using the State.

9.When should the top-class components be used for the function element?

ANS:We should employ top-class elements if your element has a stage or lifespan cycle.

10.Explain the concept of synthetic events.

ANS:It is really a cross-browser wrapper around the native event of the browser. These events have the stopPropagation() and preventDefault interfaces ().

11.What exactly is the reduction?

ANS:The reduction is a state-handling application approach.

12.What can be done when there are several lines of expression?

ANS:At that point, your only choice is to use a multi-line JSX phrase.

13.What are the main drawbacks of adopting the MVC design with React?

ANS:The following are the key issues you will face when working with MVC architecture: The cost of DOM handling is rather high. The vast majority of the time, applications were sluggish and inefficient. Because of cyclical functions, a sophisticated model based on concepts and ideas has been established.

14.What is the process by which a browser may read a JSX file?

ANS:If you want the browser to read JSX, replace the JSX file with a JSX transformer like Babel and then send it back to the browser.

15.What exactly is Babel in React JS?

ANS:Babel is a JavaScript compiler that turns the most recent JavaScript, such as ES6, ES7, into plain old ES5 JavaScript, which is understood by the majority of browsers.

16.What is the function of Webpack?

ANS:Webpack is essentially a module builder. It mostly executes throughout the development process.

17.What exactly is Context?

ANS:React context allows you to transmit data via the react component tree. It enables you to communicate data across several react components on a global scale.

18.What exactly are reacted portals?

ANS:You may render children into a DOM node using Portal. It is done using the CreatePortalmethod.

19.Describe rigorous mode.

ANS:You may use StrictMode to execute checks and warnings on react components. It only works with the development build. It allows you to highlight concerns without displaying any UI.

20.What are the error boundaries?

ANS:Error boundaries allow you to detect Javascript errors in any of the child components. They are most commonly used to record errors and provide a fallback UI.

If you're a frontend developer looking to master the basics of React.js, A2N Academy is the place to go. From the ground up, the Reactjs course will teach you the fundamentals and prepare you for the job market.