React Quiz

What is the primary purpose of `useCallback` in React?

• To memoize a component
• To memoize a function reference
• To create a new function every render
• To manage side effects

What is the difference between `useEffect` and `useLayoutEffect`?

• `useEffect` runs before paint, `useLayoutEffect` runs after
• `useLayoutEffect` runs synchronously after DOM mutations, `useEffect` runs asynchronously after paint
• They are identical
• `useLayoutEffect` is deprecated

What does `React.memo` do?

• Prevents re-rendering of a component
• Memoizes a function
• Memoizes a component and prevents re-render unless props change
• Creates a new component

What is the purpose of `key` prop in React lists?

• To style list items
• To uniquely identify elements for efficient re-rendering
• To bind data
• To handle events

What is the difference between `Context API` and `Redux`?

• Context is for global state, Redux is for local state
• Redux is built-in, Context is external
• Context is simpler and built-in, Redux is more powerful and suited for complex state
• They are interchangeable

What is the purpose of `useRef` in React?

• To create a reference to a DOM element or persist a mutable value
• To manage state
• To trigger re-renders
• To memoize a component

What is the role of `React.StrictMode`?

• To enable production optimizations
• To highlight potential problems in an application
• To disable warnings
• To enforce strict typing

What is the difference between `useState` and `useReducer`?

• `useReducer` is for simple state, `useState` is for complex state
• `useState` is for global state
• `useReducer` is preferred for complex state logic and state transitions
• They are identical

What is the purpose of `Suspense` in React?

• To delay rendering of components until a condition is met
• To handle errors
• To manage state
• To optimize performance

What is the best way to prevent unnecessary re-renders in a functional component?

• Use `useEffect`
• Use `React.memo`, `useCallback`, and `useMemo` appropriately
• Use `useState`
• Avoid using props