CognitiveClouds React Js Frontend Developer Interview Questions and Answers for Freshers

Q1. Interviewer was not letting complete my response
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Q2. If i was giving correct response, then he was interrupting and changing the question.
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Q1. Basic Questions on Project
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Q1. 1. Asked mostly related to last project that you have done
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Q1. What is props,ternary operator?
Ans. 
Props are used to pass data from parent to child components in React. Ternary operator is a conditional operator that evaluates a condition and returns one of two values.
• Props are read-only and help in maintaining the unidirectional data flow in React

• Ternary operator syntax: condition ? value if true : value if false

• Example of props:

• Example of ternary operator: const message = isTrue ?
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Q2. What is redux, explain about middleware?
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Redux is a state management library for JavaScript applications. Middleware is a function that intercepts actions before they reach the reducer.
• Redux is used to manage the state of an application in a predictable way.

• Middleware in Redux allows you to write logic that has access to the actions being dispatched.

• Common middleware in Redux includes logging, asynchronous API calls, and routing.

• Example: Redux Thunk is a popu...read more
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Q1. Questions based on the skills and position you are applying for
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Q1. Related to the positions and your skillsets which you mentioned in your resume
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Q1. Salary Discussion and your location preference
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Q1. Frontend developer
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Html, CSS, bootstrap, JavaScript, react.js

Q1. What is Virtual Dom
Ans. 
Virtual DOM is a lightweight copy of the actual DOM, used for efficient updates in React applications.
• Virtual DOM is a concept in React where a lightweight copy of the actual DOM is maintained.

• When changes are made to the virtual DOM, React compares it with the actual DOM and only updates the necessary parts.

• This helps in improving performance by minimizing the number of updates to the actual DOM.
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Q2. What is hooks and explain useEffect
Ans. 
Hooks are a new addition in React 16.8 that allow you to use state and other React features without writing a class.
• Hooks are functions that let you use state and other React features in functional components.

• useEffect is a hook that lets you perform side effects in function components.

• It is similar to componentDidMount, componentDidUpdate, and componentWillUnmount in class components.

• useEffect takes two arguments: a f...read more
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Q1. What is Cors error
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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
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Q2. Error boundaries
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Q1. Call back hell?
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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.
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