HCL Group Reactjs Developer Interview Questions and Answers

Q1. React basic,event loop, Lazy Loading, Suspense, Javascript basics
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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
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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
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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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Q1. What is client side and server side rendering
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Q1. Flat the array without using the inbuilt methods
Ans. 
Flatten an array without using inbuilt methods
• Use recursion to iterate through the array and flatten it

• Create a new array to store the flattened elements

• Check if each element is an array, if so, recursively call the function to flatten it
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Q2. Sort the given objects based on the ages
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Q1. What do you mean by redux and how to use redux
Ans. 
Redux is a predictable state container for JavaScript apps. It helps manage the state of an application in a more organized way.
• Redux is a state management tool commonly used with React to manage the state of an application.

• It follows a unidirectional data flow, where the state is stored in a single store.

• Actions are dispatched to update the state, and reducers specify how the state should change in response to actions...read more
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Q2. What is the use of Context Api in React
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Context API is used in React to pass data through the component tree without having to pass props down manually at every level.
• Avoids prop drilling by providing a way to share values like themes, user data, etc. across the component tree.

• Helps in managing global state in React applications.

• Context API consists of Provider and Consumer components to provide and consume the context data.

• Can be used for theming, localizat
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Got a link on mail to give online clearance test. 25 questions on react, Js and html-css

Q1. Build a login page
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Q1. What is the difference between states and props ?
Ans. 
States are mutable data managed within a component, while props are immutable data passed from parent to child components.
• States are managed within a component and can be changed using setState method

• Props are passed from parent to child components and are immutable

• States are used for internal component data management, while props are used for passing data between components

• Example: A counter component may have a stat...read more
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Q2. How are data passed from children to parents in react component?
Ans. 
Data can be passed from children to parents in React components by using callback functions.
• Use callback functions to pass data from child components to parent components

• Parent component passes a function as a prop to child component

• Child component calls the function with the data as an argument to pass data to parent component
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Progress bar in react and remote data fetching

Q1. Ui related questions
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Q1. Asked for preferred location and salary
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