How to add "class" to host element?
I dont't know how to add to my component <component></component> a dynamic class attribute but inside the template html (component.html).
The only solution I found is to modify the item via "ElementRef" native element. That solution seems a little complicated to do something that should be very simple.
Another problem is that CSS has to be defined outside component scope, breaking component encapsulation.
Is there a simpler solution? Something like <root [class]="..."> .... </ root> inside the template.
Answer
This way you don't need to add the CSS outside of the component:
@Component({
selector: 'body',
template: 'app-element',
// prefer decorators (see below)
// host: {'[class.someClass]':'someField'}
})
export class App implements OnInit {
constructor(private cdRef:ChangeDetectorRef) {}
someField: boolean = false;
// alternatively also the host parameter in the @Component()` decorator can be used
@HostBinding('class.someClass') someField: boolean = false;
ngOnInit() {
this.someField = true; // set class `someClass` on `<body>`
//this.cdRef.detectChanges();
}
}
This CSS is defined inside the component and the selector is only applied if the class someClass is set on the host element (from outside):
:host(.someClass) {
background-color: red;
}