W3cubDocs

/Angular

HostListener

decorator

Decorator that declares a DOM event to listen for, and provides a handler method to run when that event occurs.

Option Description
eventName?

The DOM event to listen for.

args?

A set of arguments to pass to the handler method when the event occurs.

Options

The DOM event to listen for.

eventName?: string

A set of arguments to pass to the handler method when the event occurs.

args?: string[]

Usage notes

The following example declares a directive that attaches a click listener to a button and counts clicks.

@Directive({selector: 'button[counting]'})
class CountClicks {
  numberOfClicks = 0;

  @HostListener('click', ['$event.target'])
  onClick(btn) {
    console.log('button', btn, 'number of clicks:', this.numberOfClicks++);
 }
}

@Component({
  selector: 'app',
  template: '<button counting>Increment</button>',
})
class App {}

The following example registers another DOM event handler that listens for key-press events.

import { HostListener, Component } from "@angular/core";

@Component({
  selector: 'app',
  template: `<h1>Hello, you have pressed keys {{counter}} number of times!</h1> Press any key to
increment the counter.
  <button (click)="resetCounter()">Reset Counter</button>`
})
class AppComponent {
  counter = 0;
  @HostListener('window:keydown', ['$event'])
  handleKeyDown(event: KeyboardEvent) {
    this.counter++;
  }
  resetCounter() {
    this.counter = 0;
  }
}

© 2010–2020 Google, Inc.
Licensed under the Creative Commons Attribution License 4.0.
https://angular.io/api/core/HostListener