What is Property Binding in Angular?

Q: What is property binding in Angular?

Property binding is a one-way binding that allows Angular components to pass data to HTML element properties.

Q: How does property binding differ from interpolation?

Interpolation sets inner text content, while property binding sets DOM element properties.

💡 Concept Name

Property Binding – a one-way data binding technique in Angular that binds component data to DOM element properties.

📘 Quick Intro

Property binding allows you to dynamically assign values to HTML element properties from your Angular component using square brackets syntax like [property]. It helps create responsive, interactive UIs.

🧠 Analogy / Short Story

Think of a remote control (component) changing a TV channel (DOM element). You set the channel from the remote — the TV reflects it. Similarly, property binding sets the value from component to DOM.

🔧 Technical Explanation

🔗 Uses [property] syntax to bind component fields to DOM properties.
🔁 It's one-way: data flows from component to view only.
📌 Commonly used for setting image sources, form values, disabled states, etc.
📤 More secure and efficient than string interpolation for property values.

🎯 Purpose & Use Case

✅ Dynamically set src for images or href for links.
✅ Enable/disable buttons based on conditions.
✅ Bind input value or component data to element properties.
✅ Style or toggle visibility using Angular expressions.

💻 Real Code Example

// component.ts
export class PropertyBindingComponent {
  imageUrl = 'https://example.com/angular-logo.png';
  isDisabled = true;
}

<!-- template.html -->
<img [src]="imageUrl" alt="Angular Logo" />
<button [disabled]="isDisabled">Click Me</button>

❓ Interview Q&A

Q1: What is property binding in Angular?
A: It’s a way to bind data from the component to DOM element properties using [property] syntax.

Q2: How does property binding differ from interpolation?
A: Property binding binds to actual DOM properties; interpolation binds to text content only.

Q3: Is property binding one-way or two-way?
A: One-way (component ➝ view).

Q4: Can you bind to custom component inputs using property binding?
A: Yes, using the same [input] syntax.

Q5: What happens if the property value is null or undefined in binding?
A: The DOM property becomes empty or invalid depending on its behavior.

📝 MCQs

Q1. Which syntax is used for property binding?

{property}
(property)
[property]
#property

Q2. What is the direction of data flow in property binding?

DOM to Component
Two-way
Component to DOM
DOM to Service

Q3. What is a valid use case for property binding?

Create routes
Define modules
Dynamically set an image src
Write services

Q4. What happens if you use property binding on a disabled button?

It changes text
It disables the button based on the value
It emits an event
It adds a class only

Q5. Is property binding safer than interpolation in terms of security?

No
Yes
Only for styles
Only for images

💡 Bonus Insight

Use property binding instead of interpolation when working with non-string attributes like [disabled] or [value]. It ensures proper binding to the DOM API, improving performance and accuracy.

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