JavaScript expressions in templates in Vue - Cheat Sheet & Quick Revision

Recall & Review

beginner

What can you use inside Vue template expressions?

You can use JavaScript expressions like variables, arithmetic operations, method calls, and ternary operators inside double curly braces {{ }} in Vue templates.

beginner

Can you use statements like if or for loops directly inside Vue template expressions?

No, Vue template expressions only allow JavaScript expressions, not statements like if or for loops. For control flow, Vue provides directives like v-if and v-for.

beginner

How do you write a ternary expression inside a Vue template to show 'Yes' if a variable is true, otherwise 'No'?

You write it like this: {{ isTrue ? 'Yes' : 'No' }} where isTrue is a data property or computed value.

intermediate

Why should you keep expressions in Vue templates simple and fast?

Because Vue evaluates these expressions often during rendering, complex or slow expressions can hurt performance and make your app less responsive.

beginner

How can you call a method inside a Vue template expression?

You can call a method defined in your component like this: {{ methodName() }}. The method should return a value to display.

Which of these can you use inside Vue template expressions?

A Variables and arithmetic operations

B for loops

C if statements

D Function declarations

Vue template expressions allow variables and arithmetic operations but not statements like for loops or if statements.

How do you write a conditional expression inside Vue templates?

A {{ if (x) 'Yes' else 'No' }}

B {{ x if 'Yes' else 'No' }}

C {{ x && 'Yes' || 'No' }}

D {{ x ? 'Yes' : 'No' }}

The ternary operator (condition ? trueValue : falseValue) is the correct way to write conditionals inside Vue template expressions.

What happens if you put a complex expression inside a Vue template?

A Vue ignores it

B It may slow down rendering

C It improves performance

D It causes a syntax error

Complex expressions can slow down rendering because Vue evaluates them often.

Can you call a method inside Vue template expressions?

A Yes, like {{ methodName() }}

B No, methods cannot be called

C Only if the method is async

D Only inside v-if directives

You can call methods inside template expressions to get dynamic values.

Which Vue directive should you use for loops instead of inside template expressions?

A v-if

B v-show

C v-for

D v-bind

v-for is the directive used for looping over lists in Vue templates.

Explain how JavaScript expressions work inside Vue templates and what you can and cannot do with them.

Think about what Vue allows inside double curly braces and what it does not.

Describe why keeping expressions simple in Vue templates is important and how you can handle complex logic instead.

Consider how Vue updates the UI and how complex expressions affect that.