What is Interpolation in Angular?
💡 Concept Name
Interpolation in Angular – A syntax used to display dynamic values from the component in the HTML template.
📘 Quick Intro
Interpolation in Angular allows you to embed expressions into HTML using double curly braces like {{ expression }}. It helps display data from the component to the user interface.
🧠 Analogy / Short Story
Think of interpolation as a dynamic sticker label machine. You write a label with a placeholder like {{name}}, and it automatically prints the actual name from your records—dynamic labeling in action!
🔧 Technical Explanation
- 🧩 Uses double curly braces
{{ }}to bind data to the template. - ⚙️ Evaluates expressions defined in the component class.
- 🛡️ Safe from XSS since Angular automatically escapes HTML.
- 📌 Used for string concatenation, arithmetic, method calls, etc.
- 🚫 Cannot contain statements (e.g., assignments, conditionals).
🎯 Purpose & Use Case
- ✅ Display dynamic values (name, title, status) in HTML.
- ✅ Bind computed properties or results of methods.
- ✅ Use inside attribute values or text nodes in templates.
💻 Real Code Example
// app.component.ts
export class AppComponent {
title = 'Angular Interpolation';
user = {
name: 'Ravi',
age: 30
};
}
// app.component.html
<h1>{{ title }}</h1>
<p>Welcome, {{ user.name }}. You are {{ user.age }} years old.</p>
❓ Interview Q&A
Q1: What is interpolation in Angular?
A: It is a technique to bind component data to HTML using double curly braces.
Q2: What syntax is used for interpolation?
A: {{ expression }}
Q3: Can we execute JavaScript code inside interpolation?
A: No, only expressions—not full JS code.
Q4: Is interpolation secure against XSS?
A: Yes, Angular escapes HTML automatically.
Q5: Where can interpolation be used?
A: In text nodes and attribute values in templates.
📝 MCQs
Q1. What symbol is used for interpolation in Angular?
- Square brackets
- Double curly braces
- Parentheses
- Angle brackets
Q2. What is the purpose of interpolation?
- To call APIs
- To apply CSS
- To display component data in the template
- To loop through arrays
Q3. Can you run statements in interpolation?
- Yes
- No
- Sometimes
- Only in inputs
Q4. Is Angular interpolation automatically HTML-escaped?
- No
- Yes
- Only for strings
- Depends on the tag
Q5. Where is interpolation used?
- Modules
- Templates
- Services
- Routes
💡 Bonus Insight
You can combine interpolation with string literals and also call methods or access nested properties directly within {{ }}. But avoid complex logic for performance reasons.
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