Ternary operator in Javascript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the ternary operator in JavaScript?

The ternary operator is a shortcut for an if-else statement. It uses the syntax: condition ? valueIfTrue : valueIfFalse.

beginner

How do you write a ternary operator to check if a number is even or odd?

Example: <code>let result = (num % 2 === 0) ? 'Even' : 'Odd';</code> This sets result to 'Even' if num is even, otherwise 'Odd'.

intermediate

Can the ternary operator be nested in JavaScript?

Yes, you can nest ternary operators inside each other, but it can make code hard to read. Example: <code>let result = score > 90 ? 'A' : score > 80 ? 'B' : 'C';</code>

beginner

What is the return value of a ternary operator?

The ternary operator returns the value of either the expression after the question mark if true, or the expression after the colon if false.

beginner

Why use the ternary operator instead of if-else?

It makes simple conditional assignments shorter and easier to read, especially when assigning values based on a condition.

What does the ternary operator syntax look like?

A condition ? valueIfTrue : valueIfFalse

B if (condition) { valueIfTrue } else { valueIfFalse }

C condition : valueIfTrue ? valueIfFalse

D valueIfTrue ? condition : valueIfFalse

The ternary operator uses the syntax: condition ? valueIfTrue : valueIfFalse.

What will this code return? <br> let x = 5; let result = (x > 3) ? 'Yes' : 'No';

A 'No'

B 5

C undefined

D 'Yes'

Since 5 is greater than 3, the condition is true, so 'Yes' is returned.

Can ternary operators replace all if-else statements?

A Yes, always

B No, only simple conditions

C Only in loops

D Only with numbers

Ternary operators are best for simple conditions; complex logic is clearer with if-else.

What happens if the condition in a ternary operator is false?

A The value after the colon is returned

B The value after the question mark is returned

C An error occurs

D The condition is re-evaluated

If the condition is false, the expression after the colon is returned.

Is this a valid ternary operator? <br> let a = 10; let b = a > 5 ? 'big' : 'small';

A No

B Only if a is a string

C Yes

D Only if a is less than 5

This is a valid ternary operator checking if a is greater than 5.

Explain how the ternary operator works and give a simple example.

Think of it as a short if-else that picks one of two values.

Describe when you should use the ternary operator instead of if-else statements.

Use it for quick decisions, not for complicated choices.