Shirdi Sai Electricals R&D Manager Interview Questions and Answers

Q1. What are the lifecycle methods?
Ans. 
Lifecycle methods are methods that are automatically called at certain points in the lifecycle of a component in React.
• Lifecycle methods include componentDidMount, componentDidUpdate, componentWillUnmount, etc.

• These methods allow developers to perform actions at specific points in a component's lifecycle, such as fetching data after the component has been rendered.

• They are used to manage side effects, perform cleanup, ...read more
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Q2. What are the advantages and features of react?
Ans. 
React is a popular JavaScript library for building user interfaces.
• Component-based architecture for reusability and easy maintenance

• Virtual DOM for efficient updates and performance optimization

• JSX syntax for writing HTML within JavaScript

• One-way data binding for predictable data flow

• Support for server-side rendering for improved SEO

• Large community and ecosystem with many third-party libraries and tools
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Q3. Difference between class and functional components?
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Class components are ES6 classes that extend from React.Component and have state and lifecycle methods, while functional components are simple functions that take props as input and return JSX.
• Class components are defined using ES6 classes and have a render method.

• Functional components are defined as simple functions that take props as input and return JSX.

• Class components can have state and lifecycle methods like comp...read more
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Q4. What are the Higher order components?
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Higher order components are functions that take a component and return a new component with additional functionality.
• Higher order components enhance the functionality of existing components

• They can be used for code reusability and separation of concerns

• Examples include withRouter from React Router and connect from React Redux
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Q5. What are the React hooks?
Ans. 
React hooks are functions that let you use state and other React features without writing a class.
• React hooks were introduced in React 16.8.

• They allow you to use state and other React features in functional components.

• Some commonly used hooks are useState, useEffect, useContext, and useReducer.

• Hooks are more flexible and easier to use compared to class components.
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Q6. What is the difference between contextAPI and Redux?
Ans. 
ContextAPI is a built-in feature in React for managing global state, while Redux is a separate library for state management in React applications.
• ContextAPI is built into React, while Redux is a separate library.

• ContextAPI is primarily used for managing global state in a React application.

• Redux provides a centralized store for state management and follows a unidirectional data flow.

• ContextAPI is simpler to use for smal...read more
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Q7. What are the semantic elements in html?
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Semantic elements in HTML are tags that clearly define the content they wrap, providing meaning to both browsers and developers.
• Semantic elements help improve SEO by providing search engines with better understanding of the content.

• Examples of semantic elements include <header>, <footer>, <article>, <section>, <nav>, <aside>, <main>, <figure>, <figcaption>, <deta...read more
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Q8. What are the pseudo elements?
Ans. 
Pseudo elements are used in CSS to style specific parts of an element.
• Pseudo elements are denoted by double colons (::) in CSS.

• They allow styling of specific parts of an element, like the first letter or line.

• Common pseudo elements include ::before, ::after, ::first-line, and ::first-letter.
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Q9. What is box model?
Ans. 
The box model is a fundamental concept in CSS that defines the layout of elements on a webpage.
• The box model consists of content, padding, border, and margin.

• Content: the actual content of the element, such as text or images.

• Padding: space between the content and the border.

• Border: a line that goes around the padding and content.

• Margin: space outside the border, separating the element from other elements.
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Q10. What is hoisting?
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Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their containing scope during the compilation phase.
• Variable and function declarations are hoisted to the top of their scope.

• Only declarations are hoisted, not initializations.

• Function declarations take precedence over variable declarations.

• Example: console.log(myVar); var myVar = 10; // Output: undefined

• Example: cons...read more
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Q11. What is difference between normal function and arrow function?
Ans. 
Normal functions are defined using the function keyword, while arrow functions are defined using the => syntax.
• Normal functions are hoisted, while arrow functions are not hoisted.

• Arrow functions do not have their own 'this' keyword, they inherit it from the parent scope.

• Arrow functions do not have their own 'arguments' object.

• Arrow functions are more concise and have implicit return.

• Arrow functions cannot be used as co...read more
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Q12. What is splice and slice?
Ans. 
Splice and slice are methods used in programming to manipulate arrays.
• Splice is used to add or remove elements from an array at a specific index.

• Slice is used to extract a portion of an array and returns a new array.

• Example of splice: array.splice(2, 0, 'new element') - adds 'new element' at index 2.

• Example of slice: array.slice(1, 4) - extracts elements from index 1 to 3.
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Coding questions on Java script like array methods and objects handling. coding questions on React is like life cycle methods using functional components and state management.

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