Quiz for Logical && Operator

Q1: What does the && operator do in JSX?

A. Evaluates both sides and returns true or false B. Always returns true C. Returns the right-hand side if the left is truthy D. Throws an error if left side is false

Q2: Which of the following is the correct use of && in JSX?

A. {isLoggedIn && <Dashboard />} B. {<Dashboard /> && isLoggedIn} C. {isLoggedIn || <Dashboard />} D. {isLoggedIn ? <Dashboard />} else <Login />

Q3: If isVisible is false, what will {isVisible && <p>Hello</p>} render?

A. <p>Hello</p> B. false C. null or nothing D. undefined

Q4: What is the type of value returned by logical && in JavaScript?

A. Boolean B. Left operand always C. Right operand or false D. null

Q5: Why is && preferred over if/else in JSX?

A. Simplifies return statements B. More efficient C. JSX does not allow if/else D. It is mandatory

Q6: What is rendered when using {false && <span>Hi</span>}

A. <span>Hi</span> B. false C. Nothing D. null

Q7: Which value will cause rendering of the right-hand JSX element?

A. null B. 0 C. true D. false

Q8: Can && be used inside JSX return statements?

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

Q9: What happens when you use a number like 0 with &&?

A. It throws error B. It renders 0 C. Nothing is rendered D. Renders true

Q10: Which operator is better for rendering optional elements?

A. || B. == C. && D. !==

Q11: Which is falsy in JavaScript?

A. true B. 1 C. undefined D. non-empty string

Q12: Which of these will render the <p> tag?

A. {user && <p>Welcome</p>} B. {<p>Welcome</p> && user} C. {!user && <p>Welcome</p>} D. {user ? false : <p>Welcome</p>}

Q13: What does {items.length > 0 && <List items={items} />} do?

A. Always renders List B. Never renders List C. Renders List if items.length > 0 D. Renders List if items.length == 0

Q14: Which returns undefined in JSX using &&?

A. false && <div>Hi</div> B. true && <div>Hi</div> C. 1 && <div>Hi</div> D. "hello" && <div>Hi</div>

Q15: What is a potential pitfall of using && with non-boolean values?

A. It always throws error B. It may render the non-boolean value C. It only works with strings D. React ignores it

Q16: In which case will JSX output <div>Hi</div>?

A. {true && <div>Hi</div>} B. {false && <div>Hi</div>} C. {0 && <div>Hi</div>} D. {null && <div>Hi</div>}

Q17: Is && operator allowed outside JSX?

A. Yes, in expressions B. No, only in JSX C. Only in hooks D. Only in return

Q18: What does {null && <Component />} output?

A. null B. <Component /> C. false D. undefined

Q19: What does {true && false} return?

A. true B. false C. null D. error

Q20: When is it better not to use && in JSX?

A. When both values are strings B. When checking for 0 values C. When using ternary D. Never