Ness Digital Engineering Reactjs Developer Interview Questions and Answers

Q1. Alternative way for prop drilling
Ans. 
Context API or Redux can be used as alternative ways for prop drilling in React.
• Use Context API to pass data down the component tree without having to manually pass props at every level.

• Implement Redux to manage global state and access data from any component without prop drilling.

• Consider using React's useContext hook with Context API for a simpler way to consume context in functional components.
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Q1. Asked four programs
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Q1. Salary discussion
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Q1. Basic question from React JS, Redux, Javascript, HTML and CSS.
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Q2. Core concept like difference between virtual dom and real dom.
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Q3. What is Redux and flow of Redux. Difference between context api and Redux.
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Q1. Project related questions like what had you done in previous project.
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Q2. Some scenarios based questions.
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Q1. General HR questions.
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Q1. About CI-CD , JS browser working ,
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Q2. React basics like working and jsx
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Q1. What is closures, Hoisting with example Semantic elements
Ans. 
Closures and hoisting are important concepts in JavaScript.
• Closures refer to the ability of a function to access variables in its outer scope even after the function has returned.

• Hoisting is the behavior of moving variable and function declarations to the top of their respective scopes.

• Example of closures: function outer() { let x = 10; function inner() { console.log(x); } return inner; } const innerFunc = outer(); inn...read more
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Q2. Chaining Methods Currying Call bind and apply Optimization of application Server side rendering
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Q3. Selectors HTML 5 features
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Q1. What is conditional rendering in React? What are closures? OOPS concept in JavaScript. What is ACID in database? Stack vs Heap
Ans. 
Conditional rendering in React allows components to render different elements or components based on certain conditions.
• Conditional rendering is achieved using JavaScript expressions inside JSX.

• Common conditional rendering techniques include using if statements, ternary operators, and logical && operator.

• Example: rendering a component only if a certain condition is met - {condition ? : null}
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Q2. In react you can conditionally render component like when and which component to render by using if condition and other.
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React js and JavaScript scenarios based problems.

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
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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
Ans. 
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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