有条件地将 class 应用到组件主机

Question

I'm trying to apply a class to the component tag only if something is true.

How I could turn this host into a conditional host so that I will apply the desired class when needed?

@Component({
  selector: 'k-sidebar',
  host: {
   class: '{{isChanged}}'
 },
 templateUrl: './ng-k-side-bar.component.html',
 encapsulation: ViewEncapsulation.None

})

Answer 1

You can set the host element class conditionally with @HostBinding :

condition: boolean = true;

@HostBinding("class") private get hostClass(): string {
  return this.condition ? "redBorder" : "";
}

or for a specific class name (eg redBorder ):

@HostBinding("class.redBorder") private get hasRedBorder(): boolean {
  return this.condition;
}

See these two demos: stackblitz 1 , stackblitz 2 .

Answer 2

if 'my-class' is a class name you setup it like this

@Component({
  selector: 'k-sidebar',
  host: {
   '[class.my-class]': 'isChanged'
 },
 templateUrl: './ng-k-side-bar.component.html',
 encapsulation: ViewEncapsulation.None
})
export class MyComponent {
  isChanged = true;
}