Angular FAQ: Top Questions

13. What is Interpolation in Angular?

Interpolation in Angular is a data binding technique that allows you to embed and display dynamic component data within the HTML template. It uses the double curly braces syntax — {{ expression }} — to evaluate and render JavaScript-like expressions defined in the component class.

Interpolation provides a declarative and readable way to present data from your TypeScript logic directly into the DOM, helping you keep your templates expressive and intuitive.

Syntax:
- The most common syntax is {{ variable }} or {{ methodCall() }}.
- Angular evaluates the expression in the context of the component’s class.
Supported Content:
- You can use interpolation to bind:
  - String values
  - Numeric calculations
  - Method return values
  - Expressions with ternary operators, property accesses, etc.
Limitation:
- Interpolation cannot be used to set HTML attributes directly (use property binding instead).


// demo.component.ts

import { Component } from '@angular/core';

@Component({
  selector: 'app-demo',
  template: '<p>Welcome {{ userName }}!</p>'
})
export class DemoComponent {
  userName: string = 'Angular Developer';
}

Explanation of the Example Code:

The userName property is defined in the component class with the value 'Angular Developer'.
In the HTML template, the interpolation syntax {{ userName }} is used to render the value dynamically inside the paragraph tag.
When the component is rendered, the text "Welcome Angular Developer!" will appear in the DOM.
If the userName changes, Angular’s change detection system automatically updates the displayed value.

Interpolation is a fundamental and highly readable way to bind view elements to component data, supporting clean and maintainable UI development in Angular.

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