Hexaware – React JS Interview Questions

Here is the list of React JS Interview Questions which are recently asked in Hexaware company. These questions are included for both Freshers and Experienced professionals. Our React JS Training has Answered all the below Questions.

1. What Are Components In Reactjs?

Components are independent, reusable bits of code and serve as JavaScript functions and return HTML via a render() function. The two types of components are Class components and Function components.

2. How To Apply Validation On Props In Reactjs?

React Props Validation

App. propTypes is used for props validation in react component.
App.js.
Main.js.
Output:

3. What Are State And Props In Reactjs?

Components receive data from outside with props, whereas they can create and manage their own data with state. Props are used to pass data, whereas state is for managing data. Data from props is read-only, and cannot be modified by a component that is receiving it from outside.

4. What Is The Difference Between The State And Props In Reactjs?

Props are immutable, while state is mutable. Components are responsible for the props of its child components down the component tree. On the other hand, a stateful component changes its state every time users interact with the app.

5. What Are The Benefits Of Redux?

Advantages of using Redux:

Centralized state management system i.e. Store: React state is stored locally within a component.
Performance Optimizations: Whenever a component is updated, React re-renders all the components inside that part of the component tree.

6. What Is Redux Change Of State?

The only way to update a state inside a store is to dispatch an action and define a reducer function to perform tasks based on the given actions. Once dispatched, the action goes inside the reducer functions which performs the tasks and return the updated state to the store. This is what Redux is all about.

7. Where Can Redux Be Used?

Redux can be used as a data store for any UI layer. The most common usage is with React and React Native, but there are bindings available for Angular, Angular 2, Vue, Mithril, and more. Redux simply provides a subscription mechanism which can be used by any other code.

8. What Is Store In Redux?

A store holds the whole state tree of the application. The only way to change the state inside is to dispatch an action on it. A store is not a class, just an object with a few methods on it.

9. Define ReactJs and Its features.

React is a free and open-source front-end JavaScript library for building user interfaces or UI components and can be used as a base in the development of single-page or mobile applications. It is maintained by Facebook and a community of individual developers and companies.

Features of React JS

The Virtual DOM.
One-way Data Binding, Components.
JSX, Conditional Statements.
Lifecycle Methods.

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10. Why should we use React, tell its advantages too?

React JS is a stronger framework because of its ability to break down the complex interface, complicated UI and allow users to work on individual components rather than operating on the entire web framework.

11. Enlist React limitations if you know any?

React is not a framework but a set of JavaScript libraries.
JavaScript Libraries are large in size so designers take time to understand this library.
It can be difficult to understand this library for novice programmers.
Inline templating and JSX makes the coding somewhat complex.

12. Explain Virtual DOM of React and how does it work?

React uses virtual DOM to enhance its performance and uses the observable to detect state and prop changes. React uses an efficient diff algorithm to compare the versions of virtual DOM and then makes sure that batched updates are sent to the real DOM for repainting or re-rendering of the UI.

13. What is the difference between Real and Virtual DOM?

In React, for every DOM object, there is a corresponding “virtual DOM object.” A virtual DOM object is a representation of a DOM object, like a lightweight copy. A virtual DOM object has the same properties as a real DOM object, but it lacks the real thing's power to directly change what's on the screen.

14. Differentiate between React and Angular.

Angular JS is a structural framework for developing dynamic web apps, whereas React is a JavaScript library that allows building UI components. Angular JS is based on MVC (Model View Controller) whereas React is based on Virtual DOM. Angular is based on Typescript and React is based on JavaScript.

15. Define Props.

Prop is a way of passing data from parent to child component and cannot skip a layer of child components when sending a property and the child components can't send property back up to a parent as well. We can have default props in case a parent component doesn't pass down props so that they are still set.

16. Define State in React and the way it is used in React.

The state is an instance of React Component Class can be defined as an object of a set of observable properties that control the behavior of the component. React components has a built-in state object to store property values that belongs to the component. When the state object changes, the component re-renders.

17. Compare props and state.

A prop is the short form of properties which is an object of arbitrary inputs a React function component accepts as the first argument. State is data that changes over the lifetime of a specific instance of a React component.

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TOP MNC's REACT JS INTERVIEW QUESTIONS & ANSWERS

Here we listed all React JS Interview Questions and Answers which are asked in Top MNCs. Periodically we update this page with recently asked Questions, please do visit our page often and be updated in React JS.

Hexaware React JS Interview Questions