Quiz for Map Function

Q1: What is the primary use of the map() function in React?

A. To iterate over an array and return HTML elements B. To sort elements C. To filter elements D. To clone elements

Q2: Which method is commonly used with map() to render a list of components?

A. render() B. return() C. key D. ref

Q3: Which of the following is a correct way to use map in JSX?

A. {items.map(item => <li>{item}</li>)} B. {items.each(item => <li>{item}</li>)} C. {for(item in items) <li>{item}</li>} D. {items.loop(item => <li>{item}</li>)}

Q4: Why is it important to use keys when rendering lists?

A. To maintain order B. To uniquely identify elements C. To style elements D. To delete elements

Q5: What does the map function return when used in React?

A. A new array B. The same array C. A boolean D. An object

Q6: What happens if you forget to use the return keyword in map?

A. An error occurs B. undefined is returned C. The original array is changed D. The loop is skipped

Q7: What type of function is commonly passed to map?

A. Callback function B. Constructor function C. Generator function D. Arrow function only

Q8: Which React hook is often used with map to render lists from state?

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

Q9: What is the index parameter used for in map?

A. To get the current element B. To reference the array C. To get the position of the item D. To count the length

Q10: Which of these is bad practice when using map in JSX?

A. Using index as key B. Returning JSX elements C. Using arrow function D. Storing result in a variable

Q11: What type of component can be rendered using map?

A. Only functional components B. Only class components C. Any React element D. Only <div> elements

Q12: Can map be chained with other array methods like filter?

A. Yes B. No C. Only in ES6 D. Only in functional components

Q13: What is the output of [].map(()=>{})?

A. undefined B. Error C. [] D. [undefined]

Q14: What must you wrap the JSX inside map with if returning multiple elements?

A. <div> B. React.Fragment C. [] D. Any of these

Q15: What is the correct syntax to access item properties in map?

A. item->name B. item[name] C. item.name D. item::name

Q16: Which one is more efficient when rendering list of 1000 items?

A. forEach() B. map() C. while() D. for()

Q17: How does React handle reordering in a map-generated list?

A. Using indexes B. Using keys C. Using props D. Using refs

Q18: Can JSX return value from map be wrapped in ()?

A. Yes B. No C. Only in functions D. Only in classes

Q19: Which of these will cause error with map?

A. Returning undefined B. Not returning JSX C. Not providing key D. Not importing React

Q20: How many arguments can the callback of map take?

A. 1 B. 2 C. 3 D. Any number