React Developer interview questions

React is a JavaScript library for building user interfaces. It is used because it allows for efficient updating and rendering of components using a virtual DOM, promotes component-based architecture, and is maintained by a large community.

In React, a component is a reusable piece of UI that can be a class or a function, and it manages its own content, presentation, and behavior.

Hooks are functions that let you use React features like state management and lifecycle events in functional components. They include useState, useEffect, useContext, and more.

Redux is a state management library for JavaScript apps. It is used with React to manage how the application's state changes over time, facilitating better organization and predictability of data.

Performance can be optimized by using techniques like code splitting with React.lazy and Suspense, using React.memo for memorization, avoiding inline function definitions, and effectively employing useCallback and useMemo hooks.

JSX is a syntax extension for JavaScript that looks similar to HTML or XML. It's used in React to describe what the UI should look like. It makes the code more readable and easier to debug.

The virtual DOM is a lightweight copy of the actual DOM kept in memory. React uses it to apply updates without directly manipulating the DOM, resulting in faster updates and more efficient performance.

In React class components, lifecycle methods are special methods like componentDidMount, shouldComponentUpdate, componentDidUpdate, and componentWillUnmount that are invoked at different stages of a component's existence.

Forms in React are handled using controlled components, where the form's data is managed by the component's state, or uncontrolled components, where data is accessed using refs.

State is a component's local data storage that is managed within the component and can change over time. Props are inputs to a component received from parents and are read-only in the component that receives them.