bebo Technologies Reactjs Developer Interview Questions, Process, and Tips

Q1. Basics of Javascript
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Q2. Basics of React
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Q1. Difference between promise and async await ?
Ans. 
Promises are objects representing the eventual completion or failure of an asynchronous operation, while async/await is a syntactic sugar built on top of promises to write asynchronous code in a synchronous manner.
• Promises are used to handle asynchronous operations and provide a way to chain multiple asynchronous operations together.

• Async/await allows you to write asynchronous code that looks synchronous, making it eas...read more
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Q2. Event loop based a console output questions?
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Q3. UseMemo vs useCallback
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useMemo is used for memoizing expensive calculations, while useCallback is used for memoizing functions.
• useMemo is used to memoize expensive calculations and only recompute the value when the dependencies change.

• useCallback is used to memoize functions and only re-create the function when the dependencies change.

• Example: useMemo can be used to memoize the result of a complex computation, while useCallback can be used t...read more
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Q1. Difference beetween thow and new thow
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throw is used to throw an exception, new throw is used to throw an exception with a new object
• throw is used to throw an exception in JavaScript

• new throw is used to throw an exception with a new object

• Example: throw new Error('Something went wrong')
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Q2. How to add validation
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Validation in React can be added using form validation libraries, custom validation functions, or built-in HTML5 validation attributes.
• Use form validation libraries like Formik or Yup for easy validation setup

• Create custom validation functions to validate input fields based on specific requirements

• Utilize built-in HTML5 validation attributes like required, pattern, and min/max for basic validation

• Display error messages...read more
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Hacker earth test with 29 MCQs and 1 Coding Question

Q1. What are hooks in reactjs?
Ans. 
Hooks are a new feature 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.

• They allow you to reuse stateful logic without changing your component hierarchy.

• Some built-in hooks include useState, useEffect, useContext, etc.

• Hooks provide a more direct API to the React concepts you already kn...read more
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Q2. What is pure component?
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Pure component is a class component that does not re-render if the input props and state remain the same.
• Pure components implement shouldComponentUpdate method with shallow prop and state comparison.

• They are optimized for performance as they prevent unnecessary re-renders.

• Example: class MyComponent extends React.PureComponent { // component code here }
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Q3. What is modules in javascript?
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Modules in JavaScript are reusable pieces of code that can be exported from one file and imported into another.
• Modules help in organizing code into separate files for better maintainability.

• Modules can be imported using 'import' keyword and exported using 'export' keyword.

• Modules can be used to encapsulate code and prevent global namespace pollution.

• CommonJS and ES6 modules are two popular module systems in JavaScript.
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Q4. What is the difference between rem and em in css? How to hide something in CSS?
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rem and em are both units in CSS for defining font sizes, with rem being relative to the root element and em being relative to the parent element.
• rem stands for 'root em' and is relative to the font size of the root element (usually the tag)

• em stands for 'element em' and is relative to the font size of the parent element

• To hide something in CSS, you can use the display property with a value of 'none' or the visibility...read more
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