@angular/core

HostListener

decorator

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

  
    class HostListener {}

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

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.

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 Enter key-press events on the global window.

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

The list of valid key names for keydown and keyup events can be found here: https://www.w3.org/TR/DOM-Level-3-Events-key/#named-key-attribute-values

Note that keys can also be combined, e.g. @HostListener('keydown.shift.a').

The global target names that can be used to prefix an event name are document:, window: and body:.

eventName

string

The DOM event to listen for.

args

string[]

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