App Innovation Technologies Reactjs Developer Interview Questions and Answers

Splice is used to add/remove elements from an array, while slice is used to extract a portion of an array without modifying the original array.

• Splice modifies the original array, while slice does not.

• Splice can add elements, remove elements, or replace elements in an array.

• Slice returns a new array with the selected elements from the original array.

• Example: const arr = [1, 2, 3, 4, 5]; arr.splice(2, 1); // removes elem...read more

To reverse a string, iterate through the characters and swap them from start to end.

• Create an empty string to store the reversed result.

• Iterate through the characters of the input string from end to start.

• Append each character to the empty string to reverse the order.

• Return the reversed string.

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

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

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

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

Arrow functions are used for concise syntax, lexical scoping of 'this', and implicit return of single expressions.

• Arrow functions have a more concise syntax compared to traditional function expressions.

• Arrow functions do not bind their own 'this' value, instead they inherit 'this' from the containing scope.

• Arrow functions automatically return the result of a single expression without needing the 'return' keyword.

Destructuring syntax allows for easy extraction of values from arrays or objects in JavaScript.

• Simplifies code by providing a concise way to extract multiple values from arrays or objects

• Improves readability and maintainability of code

• Can be used in function parameters to destructure objects directly

• Example: const person = { name: 'John', age: 30 }; const { name, age } = person;

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

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

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

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.

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