What does JSX stand for in React?

• JavaScript XML
• Java Syntax Extension
• Java Standard XML
• JSON Syntax Extension

Which command is used to create a new React application?

• npm create-react
• react init
• npx create-react-app my-app
• npm init react

What is a component in React?

• A function only
• A part of HTML
• A reusable piece of UI
• A JavaScript variable

Props in React are:

• Mutable
• Passed from parent to child
• Used only in class components
• Local to the component

Which hook is used to manage state in functional components?

• useEffect
• useClass
• useProps
• useState

What is the purpose of PropTypes in React?

• Styling components
• Enforcing type safety on props
• Updating state
• Routing

Which hook is used to manage side effects in functional components?

• useEffect
• useState
• useReducer
• useMemo

What does useState return?

• A state value and function to update it
• Only a function
• A reducer
• JSX and props

What is the purpose of useRef?

• Navigate routes
• Track DOM nodes or persist mutable values
• Re-render components
• Create state

Which is true about controlled components in React?

• DOM handles form data
• Form data is handled by React
• No validation possible
• Used in class only

What is a Higher-Order Component (HOC) in React?

• A new React Hook
• A component enhancer
• A DOM API
• A JSX Compiler

Which hook is best for performance optimization in functional components?

• useState
• useEffect
• useCallback
• useRef

What does React.memo do?

• Avoids prop drilling
• Prevents re-renders
• Adds lifecycle methods
• Adds delay to rendering

When using Context API, which hook is used to consume context data?

• useEffect
• useContext
• useReducer
• useCallback

What is the main goal of React Fiber?

• Server rendering
• UI design
• Reconciliation engine rewrite
• DOM manipulation