Text interpolation with mustache syntax in Vue - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is text interpolation in Vue using mustache syntax?

Text interpolation in Vue with mustache syntax means placing double curly braces {{ }} in the template to display dynamic data or variables inside HTML.

beginner

How do you display a variable named message in Vue template using mustache syntax?

You write {{ message }} inside the template. Vue replaces it with the current value of the message variable.

intermediate

Can you use JavaScript expressions inside mustache interpolation in Vue?

Yes, you can use JavaScript expressions (e.g., {{ price * 2 }}, {{ ok ? 'YES' : 'NO' }}, {{ message.split('').reverse().join('') }}) inside {{ }}. Statements (e.g., if/else) are not allowed. For complex logic, use computed properties or methods.

beginner

What happens if the variable inside mustache interpolation is undefined or null?

Vue renders an empty string if the variable is undefined or null, so nothing appears in the place of the interpolation.

beginner

Why is mustache syntax interpolation useful in Vue templates?

It lets you easily show dynamic data in the HTML without writing extra JavaScript code. It keeps the template clean and readable, like filling blanks in a letter with real values.

How do you write text interpolation for a variable name in Vue template?

A {{ name }}

B [[ name ]]

C <%= name %>

D ${name}

Vue uses double curly braces {{ }} for text interpolation.

What will Vue render if the variable inside {{ }} is undefined?

A An empty string

B An error message

C The word 'undefined'

D The variable name as text

Vue renders an empty string when the variable is undefined or null.

Can you write this inside mustache interpolation: {{ price * 2 }}?

A No, mustache interpolation only supports simple variables or properties

B Yes, but only if price is a number

C Yes, Vue supports all JavaScript expressions inside {{ }}

D No, you must use v-bind for expressions

Vue supports valid JavaScript expressions inside {{ }}, including arithmetic like price * 2.

Which of these is a correct use of mustache syntax in Vue?

A <p>{ user.name }</p>

B <p>{{ user.name }}</p>

C <p>[[ user.name ]]</p>

D <p>${user.name}</p>

Vue uses {{ }} for interpolation, so {{ user.name }} is correct.

Why should you avoid complex logic inside mustache interpolation?

A Because Vue does not allow any JavaScript in templates

B Because it causes syntax errors

C Because mustache syntax is deprecated

D Because it makes templates hard to read and debug

Complex logic should be in computed properties or methods to keep templates clean and readable.

Explain how text interpolation with mustache syntax works in Vue and why it is useful.

Think about how you fill in blanks in a letter with real names or values.

Describe the limitations of using mustache syntax for expressions in Vue templates and how to handle complex logic instead.

Remember mustache syntax is for simple display, not calculations.

Practice

1. What does the mustache syntax {{ message }} do in a Vue template?

easy

A. It displays the value of the variable message inside the HTML.

B. It creates a new variable called message.

C. It comments out the text inside the braces.

D. It runs a JavaScript function named message.

Solution

1. Step 1: Understand mustache syntax purpose

   The mustache syntax {{ }} is used in Vue to insert data values into HTML templates.

2. Step 2: Identify what {{ message }} does

   It shows the current value of the variable named message in the rendered HTML.

3. Final Answer:

   It displays the value of the variable message inside the HTML. -> Option A

4. Quick Check:

   Mustache syntax = display variable value [OK]

Hint: Mustache {{ }} always shows variable content in HTML [OK]

Common Mistakes:

• Thinking it creates variables
• Assuming it runs functions
• Confusing it with comments

2. Which of the following is the correct way to display a variable title inside a Vue template using mustache syntax?

easy

A. [[ title ]]

B. { title }

C. {{ title }}

D. {% title %}

Solution

1. Step 1: Recall Vue interpolation syntax

   Vue uses double curly braces {{ }} to insert variables into templates.

2. Step 2: Match the correct syntax

   Only {{ title }} matches Vue's mustache syntax for interpolation.

3. Final Answer:

   {{ title }} -> Option C

4. Quick Check:

   Vue interpolation = {{ variable }} [OK]

Hint: Vue uses double curly braces {{ }} for interpolation [OK]

Common Mistakes:

• Using single braces instead of double
• Confusing with other template syntaxes
• Using wrong bracket types

3. Given the Vue data: { name: 'Anna' }, what will be rendered by this template?

<div>Hello, {{ name }}!</div>

medium

A. Hello, {{ name }}!

B. Hello, Anna!

C. Hello, name!

D. Hello, !

Solution

1. Step 1: Identify the data value

   The variable name has the value 'Anna'.

2. Step 2: Understand interpolation output

   The mustache syntax replaces {{ name }} with 'Anna' in the rendered HTML.

3. Final Answer:

   <div>Hello, Anna!</div> -> Option B

4. Quick Check:

   Variable value replaces {{ name }} [OK]

Hint: Mustache {{ }} shows variable value, not the code itself [OK]

Common Mistakes:

• Expecting to see {{ name }} literally
• Confusing variable name with its value
• Leaving interpolation empty

4. What is wrong with this Vue template snippet?

<div>{{ user.name </div>

medium

A. Mustache syntax cannot access object properties.

B. Variable user is not defined.

C. Interpolation must use square brackets instead of curly braces.

D. Missing closing curly braces for interpolation.

Solution

1. Step 1: Check mustache syntax completeness

   The snippet has only one closing curly brace; mustache syntax requires double closing braces }}.

2. Step 2: Confirm correct syntax for interpolation

   Proper interpolation should be {{ user.name }} with both opening and closing double braces.

3. Final Answer:

   Missing closing curly braces for interpolation. -> Option D

4. Quick Check:

   Mustache needs {{ and }} to work [OK]

Hint: Always close mustache with double braces }} [OK]

Common Mistakes:

• Using single closing brace
• Forgetting to close interpolation
• Thinking square brackets are needed

5. You want to display a greeting that changes based on time using mustache syntax. Which template code correctly shows 'Good morning' if hour is less than 12, otherwise 'Good afternoon'?

hard

A. <div>{{ hour < 12 ? 'Good morning' : 'Good afternoon' }}</div>

B. <div>{{ if (hour < 12) 'Good morning' else 'Good afternoon' }}</div>

C. <div>{{ hour < 12 && Good morning || 'Good afternoon' }}</div>

D. <div>{{ hour < 12 ? Good morning : Good afternoon }}</div>

Solution

1. Step 1: Understand mustache supports JavaScript expressions

   Mustache syntax in Vue allows simple JavaScript expressions like ternary operators.

2. Step 2: Check each option for correct syntax

   <div>{{ hour < 12 ? 'Good morning' : 'Good afternoon' }}</div> uses a valid ternary expression with quotes around strings, which is correct. <div>{{ if (hour < 12) 'Good morning' else 'Good afternoon' }}</div> uses invalid syntax inside mustache. <div>{{ hour < 12 && Good morning || 'Good afternoon' }}</div> misses quotes around Good morning, causing a syntax error. <div>{{ hour < 12 ? Good morning : Good afternoon }}</div> misses quotes around strings, causing errors.

3. Final Answer:

   <div>{{ hour < 12 ? 'Good morning' : 'Good afternoon' }}</div> -> Option A

4. Quick Check:

   Ternary with quotes works in mustache [OK]

Hint: Use ternary with quotes inside {{ }} for conditional text [OK]

Common Mistakes:

• Omitting quotes around strings
• Using if-else statements inside mustache
• Using logical operators incorrectly