React JS interview question part 2

 

What are Higher Order Components (HOCs) in React?
Higher Order Components (HOCs) are functions that take a component and return a new component with additional functionality. They are used to add reusable logic to components.

What is a prop in React?
A prop is short for "property" and is used to pass data from one component to another. Props are read-only and cannot be modified by the receiving component.

How does React handle data binding?
React uses a one-way data flow, which means that data only flows in one direction (from parent to child components). To update the UI based on changes in data, React re-renders the affected components.

What are controlled components in React?
Controlled components are components that are controlled by React via their state and props. The value of a controlled component is always determined by the component's state, rather than directly from user input.

What is the significance of keys in React?
Keys are used by React to identify unique components when rendering lists. They help React efficiently update the UI by minimizing the number of DOM manipulations required.

What is the difference between props and state?
Props are used to pass data from a parent component to a child component, whereas state is used to manage data within a component. Props are read-only and cannot be modified by the child component, while state can be modified using setState().

What is the significance of using Redux in a React application?
Redux is a state management library that helps developers manage the state of their application in a predictable way. It provides a centralized store that holds the state of the entire application, making it easier to manage and debug. Redux is commonly used with React to manage the state of complex applications.

What is the difference between class components and functional components?
Class components are defined using ES6 classes and have access to lifecycle methods, state, and props. Functional components are defined using JavaScript functions and are typically simpler and easier to read. With the introduction of React Hooks, functional components can now also have state and access to lifecycle methods.

What is an event in React?
In React, events are similar to events in traditional JavaScript, but they are wrapped in a synthetic event object that is passed to the event handler. The synthetic event object contains information about the event, such as the target element and the type of event.

What is the significance of using React.memo()?
React.memo() is a higher-order component that is used to memoize a component. This means that if the component receives the same props, it will not re-render. Memoization can help improve the performance of a React application by reducing unnecessary re-renders.

What is server-side rendering in React?
Server-side rendering is a technique used to render the initial HTML of a React application on the server, rather than in the user's browser. This can help improve the performance of the application by reducing the time it takes to load the initial page.