Explain ViewEncapsulation in Angular

In Angular, ViewEncapsulation is a feature that determines how the styles defined in a component are applied and scoped to that component. It defines the level of encapsulation that is applied to a component’s styles.

There are three possible values for ViewEncapsulation in Angular:

1. ViewEncapsulation.Native: This value specifies that the component’s styles will be encapsulated using the Shadow DOM technology. This means that the styles will only be applied to the component and its children and will not leak out to the rest of the application.
2. ViewEncapsulation.Emulated: This value specifies that Angular will emulate the behavior of the Shadow DOM technology and encapsulate the component’s styles. However, instead of using the Shadow DOM, Angular will use its own implementation to scope the styles to the component.
3. ViewEncapsulation.None: This value specifies that the component’s styles will not be encapsulated and will be applied globally to the entire application.

By default, Angular components use the ViewEncapsulation.Emulated value, which provides a good balance between encapsulation and compatibility with older browsers that do not support the Shadow DOM.

Here’s an example of how to specify the ViewEncapsulation value in a component:

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

@Component({
  selector: 'app-example',
  template: `
    <h1>{{ title }}</h1>
    <button (click)="changeTitle()">Change Title</button>
  `,
  styles: [`
    h1 {
      color: red;
    }
  `],
  encapsulation: ViewEncapsulation.Emulated
})
export class ExampleComponent {
  title = 'Hello, World!';

  changeTitle() {
    this.title = 'The title has changed!';
  }
}