Wipro Reactjs Developer Interview Questions and Answers for Experienced

React and Javascript

Coding test with technical discussion

Q1. Some of important javascript questions
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Q2. On react js like hooks, virtual dom,html5 and html,state, useMemo, useCallback,useEffect
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Q3. Box model, css selector
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Q4. What are fragments in react js
Ans. 
Fragments in React.js are used to group multiple elements without adding an extra node to the DOM.
• Fragments are a way to group multiple elements without using a wrapper element.

• They help in avoiding unnecessary divs in the DOM.

• Fragments can improve performance by reducing the number of DOM nodes.

• They are useful when returning multiple elements from a component's render method.

• Fragments can be written using the
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Q1. What are the advantages of React
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React offers advantages such as virtual DOM for improved performance, reusable components, and easy integration with other libraries.
• Virtual DOM for efficient updates and improved performance

• Reusable components for easier development and maintenance

• Easy integration with other libraries like Redux for state management

• Support for server-side rendering for better SEO performance
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Q2. How the performance optimization can be done in React Js Application
Ans. 
Performance optimization in React Js can be achieved through code splitting, memoization, virtualization, and minimizing re-renders.
• Implement code splitting to load only necessary components when needed

• Use memoization techniques like useMemo and useCallback to prevent unnecessary re-renders

• Implement virtualization for long lists or tables to render only visible items

• Minimize re-renders by using shouldComponentUpdate or
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Q3. What is the purpose of useMemo and UseCallBack hook
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useMemo and useCallback are hooks in React used for optimizing performance by memoizing values and functions respectively.
• useMemo is used to memoize the result of a function so that it is only recomputed when its dependencies change.

• useCallback is used to memoize a function instance so that it is not recreated on every render unless its dependencies change.

• Both hooks help in optimizing performance by preventing unneces...read more
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Q1. I gave technical interview with Accenture for react js developer. They asked questions majorly related to software development like session storage, Server side rendering Url Constructor Saas Web workers...read more
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Q1. Why is arrow function used
Ans. 
Arrow functions are used for concise syntax, lexical scoping of 'this', and implicit return of single expressions.
• Arrow functions have a more concise syntax compared to traditional function expressions.

• Arrow functions do not bind their own 'this' value, instead they inherit 'this' from the containing scope.

• Arrow functions automatically return the result of a single expression without needing the 'return' keyword.
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Q2. What is the need of de structuring syntax
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Destructuring syntax allows for easy extraction of values from arrays or objects in JavaScript.
• Simplifies code by providing a concise way to extract multiple values from arrays or objects

• Improves readability and maintainability of code

• Can be used in function parameters to destructure objects directly

• Example: const person = { name: 'John', age: 30 }; const { name, age } = person;
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Q1. Explain useSelector
Ans. 
useSelector is a hook provided by React-Redux for accessing the Redux store state in functional components.
• Allows functional components to access the Redux store state without connecting to the store

• Accepts a selector function as an argument to specify which part of the state to extract

• Automatically subscribes to the Redux store updates and re-renders the component when the selected state changes
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Q2. Optimization in react
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Optimization in React involves improving performance and efficiency of the application.
• Use shouldComponentUpdate or PureComponent to prevent unnecessary re-renders

• Avoid using inline functions in render method to prevent re-renders

• Use keys in lists to help React identify which items have changed

• Splitting components into smaller ones can improve performance

• Use React.memo for functional components to memoize the result
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Q3. What is JSX in react
Ans. 
JSX is a syntax extension for JavaScript used in React to write HTML-like code within JavaScript.
• JSX allows developers to write HTML-like code directly in their JavaScript files

• It makes the code more readable and easier to understand

• JSX gets transpiled into regular JavaScript by tools like Babel before being rendered by the browser
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Q4. Explain redux flow in react
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Redux flow in React involves actions, reducers, store, and components to manage state in a centralized manner.
• Actions are dispatched to describe what happened in the application.

• Reducers specify how the state changes in response to actions.

• Store holds the state of the application.

• Components can connect to the store to access and update the state.
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Q5. Stateful and stateless components
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Q1. Brief about project
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Developed a web application for managing inventory and sales
• Used Reactjs for front-end development

• Implemented Redux for state management

• Integrated with backend APIs using Axios

• Designed responsive UI for better user experience
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Q2. Asked me about graph ql
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Q3. Asked topic on routing .
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