Free Test State in Class vs Func... – REACT

Q1: How is state defined in a React class component?

A. Using this.state = {} in constructor B. Using const state = {} C. Using useState() D. Using getState()

Q2: Which hook is used to manage state in functional components?

A. useReducer() B. useEffect() C. useState() D. useContext()

Q3: How is state updated in class components?

A. this.setState() B. state.update() C. setState() D. this.state()

Q4: What does useState() return?

A. A value and a setter function B. Only the value C. Only the setter D. A function and a reducer

Q5: Which is true about class component state?

A. Can be modified directly B. Should only be updated using this.setState() C. Only accessible via props D. Not persistent

Q6: Where is the state initialized in class components?

A. Inside render() B. Inside the constructor C. Inside componentDidMount() D. Inside setState()

Q7: Is it possible to use useState in class components?

A. Yes B. No C. Only with HOC D. Only after React 18

Q8: What lifecycle method is used for setting initial state in class components?

A. componentDidUpdate() B. componentDidMount() C. constructor() D. render()

Q9: Can functional components have state without hooks?

A. Yes B. No C. Only with Redux D. Only using HOC

Q10: Which is the correct syntax for useState?

A. const [state, setState] = useState() B. let state = useState() C. state = useState() D. useState(state, setState)

Q11: Which of the following is a class component?

A. function App() {} B. const App = () => {} C. class App extends React.Component {} D. App = () => {}

Q12: What is the initial argument passed to useState()?

A. A reducer B. The initial state value C. A callback function D. An array

Q13: Which method is triggered after setState updates the state in class components?

A. Immediately updated B. Component re-renders C. componentWillUnmount() D. Nothing happens

Q14: Which method is deprecated in class components?

A. componentDidMount() B. componentWillReceiveProps() C. render() D. setState()

Q15: How do you conditionally update state based on previous state in class components?

A. this.setState({ count: count + 1 }) B. this.setState(prevState => ({ count: prevState.count + 1 })) C. this.state.count++ D. setState(count + 1)

Q16: Is state mutable in React?

A. Yes B. No C. Only in class D. Only in functional

Q17: What happens if setState is called with the same value?

A. Component still re-renders B. Nothing happens C. State becomes null D. Error thrown

Q18: What hook combines reducer logic with state?

A. useState B. useEffect C. useReducer D. useRef

Q19: When to use useEffect in functional components?

A. To directly mutate state B. To fetch data or perform side effects C. To update class state D. Never

Q20: Which one provides cleaner code for small components?

A. Class component B. Functional component with hooks C. PureComponent D. HOC

Quiz for State in Class vs Functional Components