How to bind event listener for rendered elements in Angular 2?

问题

How can I bind an event listener in rendered elements in Angular 2?

I am using Dragula drag and drop library. It creates dynamic HTML but my event is not bound to dynamic HTML elements.

回答1:

import { AfterViewInit, Component, ElementRef} from '@angular/core';

constructor(private elementRef:ElementRef) {}

ngAfterViewInit() {
  this.elementRef.nativeElement.querySelector('my-element')
                                .addEventListener('click', this.onClick.bind(this));
}

onClick(event) {
  console.log(event);
}

回答2:

In order to add an EventListener to an element in angular 2+, we can use the method listen of the Renderer2 service (Renderer is deprecated, so use Renderer2):

listen(target: 'window'|'document'|'body'|any, eventName: string, callback: (event: any) => boolean | void): () => void

Example:

export class ListenDemo implements AfterViewInit { 
   @ViewChild('testElement') 
   private testElement: ElementRef;
   globalInstance: any;       

   constructor(private renderer: Renderer2) {
   }

   ngAfterViewInit() {
       this.globalInstance = this.renderer.listen(this.testElement.nativeElement, 'click', () => {
           this.renderer.setStyle(this.testElement.nativeElement, 'color', 'green');
       });
    }
}

Note:

When you use this method to add an event listener to an element in the dom, you should remove this event listener when the component is destroyed

You can do that this way:

ngOnDestroy() {
  this.globalInstance();
}

The way of use of ElementRef in this method should not expose your angular application to a security risk. for more on this referrer to ElementRef security risk angular 2

回答3:

HostListener should be the proper way to bind event into your component:

@Component({
  selector: 'your-element'
})

export class YourElement {
  @HostListener('click', ['$event']) onClick(event) {
     console.log('component is clicked');
     console.log(event);
  }
}

回答4:

If you want to bind an event like 'click' for all the elements having same class in the rendered DOM element then you can set up an event listener by using following parts of the code in components.ts file.

import { Component, OnInit, Renderer, ElementRef} from '@angular/core';

constructor( elementRef: ElementRef, renderer: Renderer) {
    dragulaService.drop.subscribe((value) => {
      this.onDrop(value.slice(1));
    });
}

public onDrop(args) {

  let [e, el] = args;

  this.toggleClassComTitle(e,'checked');

}


public toggleClassComTitle(el: any, name: string) {

    el.querySelectorAll('.com-item-title-anchor').forEach( function ( item ) {

      item.addEventListener('click', function(event) {
              console.log("item-clicked");

       });
    });

}

回答5:

@HostListener('window:click', ['$event']) onClick(event){ }

check this below link to detect CapsLock on click, keyup and keydown on current window. No need to add any event in html doc

Detect and warn users about caps lock is on

来源：https://stackoverflow.com/questions/41609937/how-to-bind-event-listener-for-rendered-elements-in-angular-2

标签

angular

addeventlistener

event-binding