Boolean Logic, Comparison Operators, and Loops Review Quiz

Michael and Harper are planning a picnic. They will go only if both the weather is sunny and they both have a day off. What does the && (AND) operator return when both conditions are true?

• true

• false

• undefined

• an error

Answer explanation

The && (AND) operator returns true when both conditions are true. Since Michael and Harper will picnic only if the weather is sunny and they both have a day off, both conditions being true results in true.

Zoe is deciding whether to go for a walk. She will only go if it is sunny and not raining. What is the result of it being sunny && raining?

• She will go for a walk

• She will not go for a walk

• undefined

• an error

Answer explanation

Zoe will not go for a walk because the condition requires it to be sunny and not raining. Since it is raining, the condition is not met.

What is the result of !(true)?

• true

• false

• null

• undefined

Answer explanation

The expression !(true) uses the logical NOT operator, which negates the value. Since true is being negated, the result is false. Therefore, the correct answer is false.

What is the output of the following JavaScript code? let x = 10; console.log(x != 10);

• true

• false

• 10

• error

Answer explanation

The code checks if x (10) is not equal to 10 using the '!=' operator. Since 10 is equal to 10, the expression evaluates to false. Therefore, the output is false.

Nora has 5 apples and she knows that 5 is greater than 3. She also has 8 oranges and knows that 8 is less than 10. What will console.log(5 > 3 && 8 < 10); print?

• true

• false

• 5

• 8

Answer explanation

The expression '5 > 3' evaluates to true and '8 < 10' also evaluates to true. The '&&' operator requires both conditions to be true, so 'true && true' results in true. Therefore, console.log(5 > 3 && 8 < 10) prints true.

Fill in the blank: In JavaScript, the expression 5 > 3 && 8 < 10 evaluates to ____.

• true

• false

• 5

• 8

Answer explanation

The expression 5 > 3 evaluates to true and 8 < 10 also evaluates to true. Since both conditions are true, the entire expression 5 > 3 && 8 < 10 evaluates to true.

Isla is writing a JavaScript program to check if a user is logged in. Fill in the blank: The correct syntax for an if statement in JavaScript is ____.

• A) if condition then {}

• B) if (condition) {}

• C) if {condition}

• D) if condition {}

Answer explanation

The correct syntax for an if statement in JavaScript is B) if (condition) {}. This format uses parentheses to enclose the condition and curly braces to define the block of code that executes if the condition is true.

What is the purpose of an else statement?

• A) To execute code only if the condition is true

• B) To execute code only if the condition is false

• C) To break out of a loop

• D) To restart the program

Answer explanation

The else statement is used to execute code when the preceding condition is false. Therefore, the correct choice is B) To execute code only if the condition is false.

Fill in the blank: In JavaScript, the else statement is used to execute code when the if condition is ____.

• A) true

• B) false

• C) undefined

• D) null

Answer explanation

The else statement in JavaScript is executed when the if condition is false. Therefore, the correct choice is B) false, as it allows for alternative code execution when the initial condition does not hold.

What is wrong with this code?

if (5 > 3);

console.log("Hello");

• The semicolon ends the if statement prematurely

• Nothing is wrong

• The console.log statement is in the wrong place

• The condition is invalid

Answer explanation

The semicolon after the if statement ends it prematurely, causing the console.log to execute unconditionally. This means 'Hello' will always be logged, regardless of the condition.