@angular/core

HostBinding

decorator

Decorator that marks a DOM property or an element class, style or attribute as a host-binding property and supplies configuration metadata. Angular automatically checks host bindings during change detection, and if a binding changes it updates the host element of the directive.

API

@HostBinding(hostPropertyName?: string);

Usage Notes

The following example creates a directive that sets the valid and invalid class, a style color, and an id on the DOM element that has an ngModel directive on it.

@Directive({selector: '[ngModel]'})class NgModelStatus {  constructor(public control: NgModel) {}  // class bindings  @HostBinding('class.valid') get valid() { return this.control.valid; }  @HostBinding('class.invalid') get invalid() { return this.control.invalid; }  // style binding  @HostBinding('style.color') get color() { return this.control.valid ? 'green': 'red'; }  // style binding also supports a style unit extension  @HostBinding('style.width.px') @Input() width: number = 500;  // attribute binding  @HostBinding('attr.aria-required')  @Input() required: boolean = false;  // property binding  @HostBinding('id') get id() { return this.control.value?.length ? 'odd':  'even'; }@Component({  selector: 'app',  template: `<input [(ngModel)]="prop">`,})class App {  prop;}