TCS Reactjs Developer Interview Questions and Answers

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
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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...read more
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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
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React js and JavaScript scenarios based problems.

Q1. Difference between if else and ternary
Ans. 
Ternary operator is a shorthand for if else statement in JavaScript.
• Ternary operator is written as condition ? expression1 : expression2

• If the condition is true, expression1 is executed, else expression2 is executed

• Ternary operator is more concise and can be used inline in JSX
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Q2. Class and functional components
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Q1. About my projects
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Q2. About strenghts and weeknesses
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Q1. About my experience
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Q2. Salary discussions
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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
Ans. 
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
Ans. 
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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