Saksoft Reactjs Developer Interview Questions and Answers

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
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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. Explain useSelector
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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
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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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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. Questions related to Current Job Profile and previous experience
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Q1. What is hoisting in JS
Ans. 
Hoisting is a JavaScript behavior where variable and function declarations are moved to the top of their containing scope.
• Hoisting applies to both variable and function declarations.

• Variable declarations are hoisted but not their initializations.

• Function declarations are fully hoisted, allowing them to be called before they are declared.

• Hoisting does not apply to variables declared with let or const.

• Hoisting can lead t...read more
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Q2. What are higher-order functions in JS
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Higher-order functions are functions that take one or more functions as arguments or return a function as their result.
• Higher-order functions can be used to create reusable code by abstracting common patterns.

• They enable functional programming paradigms like currying and composition.

• Examples of higher-order functions in JavaScript include map, filter, and reduce.
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Q3. Difference between var, let, and const in JS
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var is function scoped, let and const are block scoped.
• var can be redeclared and updated within its scope

• let can be updated but not redeclared within its scope

• const cannot be updated or redeclared once declared

• let and const are not hoisted like var

• const must be initialized during declaration
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Q4. What are Hooks in React.js
Ans. 
Hooks are a feature in React.js that allow developers to use state and other React features in functional components.
• Hooks are functions that let you use React features in functional components

• They allow you to use state and other React features without writing a class

• Hooks provide a way to reuse stateful logic between components

• Some commonly used hooks are useState, useEffect, and useContext
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Q5. Presentation component vs functional component in React.js
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Q6. Bind(), call(), apply() in JS
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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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