Quiz for Typing Props and State

Q1: How do you define props types for a functional component?

A. A. Using an interface and React.FC<Props> B. B. Using PropTypes C. C. Using "any" type only D. D. No typing needed

Q2: Which keyword is used to declare types for state in class components?

A. A. interface or type for state and props B. B. var C. C. let D. D. const

Q3: How to type a state hook for a string value?

A. A. useState<string>("") B. B. useState(0) C. C. useState([]) D. D. useState()

Q4: What type is usually used to type event handlers in React?

A. A. React.ChangeEvent<HTMLInputElement> B. B. Event C. C. MouseEvent D. D. any

Q5: How do you declare optional props in TypeScript?

A. A. Using a question mark ? in the interface B. B. Using defaultProps C. C. Using union types D. D. Not possible

Q6: Which of these is the correct way to type children prop?

A. A. React.ReactNode B. B. string C. C. any D. D. HTMLElement

Q7: What is the type of setState function returned by useState hook?

A. A. React.Dispatch<React.SetStateAction<Type>> B. B. Function C. C. any D. D. void

Q8: How to type a state that can be either a string or null?

A. A. useState<string | null>(null) B. B. useState("") C. C. useState(null) D. D. useState<any>(null)

Q9: How to type a ref to an HTML input element?

A. A. useRef<HTMLInputElement>(null) B. B. useRef(null) C. C. useRef() D. D. useState()

Q10: What type do you use for function props?

A. A. (param: Type) => ReturnType B. B. Function C. C. any D. D. void

Q11: How to type a state hook with an array of strings?

A. A. useState<string[]>([]) B. B. useState([]) C. C. useState<any[]>([]) D. D. useState(Array)

Q12: Which interface is used to type React component props?

A. A. interface Props { ... } B. B. type Props = any C. C. class Props {} D. D. const Props = {}

Q13: Can you use type aliases instead of interfaces for props?

A. A. Yes, both are valid B. B. No, only interfaces work C. C. No, only types work D. D. No typing is required

Q14: How to type a React component returning null?

A. A. React.FC<Props> or React.ReactElement | null B. B. void C. C. any D. D. never

Q15: Which type describes any React element?

A. A. React.ReactElement B. B. HTMLElement C. C. Element D. D. Node

Q16: How to define default props in functional components?

A. A. Using default parameters in function signature B. B. Using PropTypes C. C. Using no defaults D. D. Using useState

Q17: What happens if you don't type props in TypeScript?

A. A. Props are implicitly any, losing type safety B. B. Code won't compile C. C. Props are automatically typed D. D. React errors out

Q18: How to type an event for form submission?

A. A. React.FormEvent<HTMLFormElement> B. B. Event C. C. React.MouseEvent D. D. any

Q19: Which generic type is used with useReducer hook?

A. A. useReducer<ReducerType, InitialStateType> B. B. useReducer<any> C. C. useReducer() D. D. useReducer<void>

Q20: How to type a callback ref in TypeScript?

A. A. (instance: HTMLDivElement | null) => void B. B. React.RefObject C. C. any D. D. void