Senwell Solutions React Js Software Engineer Interview Questions and Answers

Q1. Explain Virtual DOM, Key Features of React, Hooks in React, create a todo app in react
Ans. 
Virtual DOM is a lightweight copy of the actual DOM, React key features include component-based architecture, declarative syntax, and virtual DOM, React Hooks are functions that let you use state and other React features without writing a class.
• Virtual DOM is a lightweight copy of the actual DOM that React uses to improve performance by updating only the necessary parts of the DOM.

• Key features of React include componen...read more
Answered by AI
Add your answer
Q2. Javascript Questions- Closures,promises,Async/await,setTimeOut, write acode to reverse a string
Add your answer

Q1. Self Introduction, some situation based questions
Add your answer
Q2. Basic HR regular questions
Add your answer

Q1. React basic,event loop, Lazy Loading, Suspense, Javascript basics
Add your answer
Q2. Create counter application
Ans. 
Counter application using Reactjs
• Create a React component for the counter

• Use state to keep track of the count

• Implement functions to increment and decrement the count

• Display the count on the screen
Answered by AI
Add your answer

Q1. What are the advantages of React
Ans. 
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
Answered by AI
Add your answer
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
Answered by AI
Add your answer
Q3. What is the purpose of useMemo and UseCallBack hook
Ans. 
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
Answered by AI
Add your answer

Q1. What is prop drilling
Ans. 
Prop drilling is the process of passing props down multiple levels of nested components in React.
• Prop drilling occurs when a prop needs to be passed through multiple levels of components that do not need the prop themselves.

• It can lead to unnecessary passing of props through intermediate components, making the code harder to maintain.

• To avoid prop drilling, you can use Context API, Redux, or React's useContext and useR...read more
Answered by AI
Add your answer
Q2. What is hoisting
Ans. 
Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their containing scope during the compilation phase.
• Variable declarations are hoisted to the top of their scope, but not their assignments.

• Function declarations are fully hoisted, meaning they can be called before they are declared.

• Hoisting can lead to unexpected behavior if not understood properly.
Answered by AI
Add your answer

Q1. Explain useContext hook
Ans. 
useContext hook allows components to access data from a context without passing props down manually
• useContext hook is used to consume a context created by React.createContext

• It takes the context object as an argument and returns the current context value for that context

• It allows components to subscribe to context changes and re-render when the context value changes
Answered by AI
Add your answer

Q1. What is Cors error
Ans. 
CORS error occurs when a web application makes a request to a different domain than the one it originated from.
• CORS stands for Cross-Origin Resource Sharing

• It is a security feature implemented by browsers to prevent unauthorized access to resources on a different domain

• CORS error can be resolved by configuring the server to include the appropriate CORS headers in the response

• Common CORS error messages include 'Access-C...read more
Answered by AI
Add your answer
Q2. Error boundaries
Add your answer

Q1. Call back hell?
Add your answer
Q2. Promises in javascript
Ans. 
Promises in JavaScript are objects representing the eventual completion or failure of an asynchronous operation.
• Promises are used to handle asynchronous operations in JavaScript.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() method to handle success and failure cases.

• Promises help in avoiding callback hell and writing cleaner asynchronous code.
Answered by AI
Add your answer

They asked , some cording question related to react js , html