TCS React JS Interview Questions

Here is the list of React JS Interview Questions which are recently asked in Cognizant company. These questions are included for both Freshers and Experienced professionals.

1. What Is Reactjs?

React is an open-source JavaScript library that is used to develop complex and interactive web and mobile UI. It is used for building web browser apps, creating dynamic libraries, and for building UI’s that are perfectly equipped to render large datasets

2. Why Reactjs Is Used?

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

3. Does Reactjs Use Html?

React js is just a part of view which eases your development. Under the hood it is all html, JavaScript and CSS. With React, we write HTML using JavaScript.

4. When Reactjs Released?

React was created by Jordan Walke, a software engineer at Facebook, who released an early prototype of React called “FaxJS”. It was first deployed on Facebook’s News Feed in 2011 and later on Instagram in 2012. It was open-sourced at JSConf US in May 2013.

5. What Is Current Stable Version Of Reactjs?

The current stable version of React JS is 17.0.2 / 22 March 2021 which is developed by Facebook and community and iinitial release is on May 29, 2013.

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6. What Are The Feature Of Reactjs?

Virtual DOM, JSX.
One-way data binding.
Declarative UI, Flexibility.
Component-based architecture.
Speed and efficiency.

7. What Are The Advantages Of Reactjs?

Easy to Learn, Easy to Use.
Reusable Components, the Virtual DOM.
Great Developer Tools.
It’s Easier to Write with JSX, the Ecosystem.

8. How To Embed Two Components In One Component?

if we have multiple elements to render, there can only be a single root element. This means if we want to render two or more elements, we have to wrap them in another element or component. Commonly, the element used for this is a div tag.

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9. What Are The Advantages Of Using Reactjs?

React JS simplifies the overall process of scripting components.
It facilitates advanced maintenance and boosts productivity.
It guarantees quicker rendering.
React JS offers a more stable code, SEO friendly.

10. What Are The Limitations Of Reactjs?

The high pace of development has an advantage and disadvantages both Poor Documentation. It is another con which is common for constantly updating technologies. View Part. React JS Covers only the UI Layers of the app and nothing else. JSX as a barrier.

11. How To Use Events In Reactjs?

Handling events with React elements is very similar to handling events on DOM elements. There are some syntax differences: React events are named using camelCase, rather than lowercase. With JSX you pass a function as the event handler, rather than a string.

12. Give An Example Of Using Events?

React events are written in camelCase syntax: onClick instead of onclick . React event handlers are written inside curly braces:

onClick={shoot} instead of onClick=”shoot()”.

13. What Is Flux Concept In Reactjs?

Flux is a programming concept, where the data is uni-directional. This data enters the app and flows through it in one direction until it is rendered on the screen.

14. What Are The Advantages Of Using Jsx?

JSX is just HTML-like syntax, it’s optional, and its purpose is to simplify the creation of React tree nodes with attributes. It lets you create JavaScript objects with HTML syntax, but JSX is not required to use React

15. What Is Reactjs-jsx?

React JS-JSX is called JSX, and it is a syntax extension to JavaScript. We recommend using it with React to describe what the UI should look like. JSX may remind you of a template language, but it comes with the full power of JavaScript. JSX produces React “elements”.

16. What Are Components In Reactjs?

Components are independent and reusable bits of code. They serve the same purpose as JavaScript functions, but work in isolation and return HTML via a render () function. Components come in two types, Class components and Function components.

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TCS React JS Interview Questions