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

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Option	Description
eventName?	The DOM event to listen for.
args?	A set of arguments to pass to the handler method when the event occurs.

Description

Angular invokes the supplied handler method when the host element emits the specified event, and updates the bound element with the result.

If the handler method returns false, applies preventDefault on the bound element.

Further information available in the Usage Notes...

Options

eventName
The DOM event to listen for.
eventName?: string

args
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;
  }
}