在ngOnDestroy中删除EventListener

Question

我有一个指令的以下实现.在这种情况下如何removeEventListener:

import { Directive, ElementRef, OnDestroy } from "@angular/core";

@Directive({
    selector: "[Enter]"
})
export class Enter implements OnDestroy{
    constructor(el: ElementRef) {
        let enter = function(event){
            if(event.keyCode === 13){
                el.nativeElement.click();
            }
        }
        document.addEventListener('keyup', enter , false);
    }

    ngOnDestroy(){
        document.removeEventListener('keyup', enter, false); //this line doesn't work because I can't access enter variable here!
    }
}

我知道我可以在这里使用全局变量并可以访问它.但我不想将实例的状态存储在全局变量中.

Answer 1

我会利用@HostListener装饰师来做到这一点:

@Directive({
  selector: "[Enter]"
})
export class Enter {
  @HostListener('document:keyup', ['$event'])
  enter(event) {
    if (event.keyCode !== 13) return;
    this.el.nativeElement.click();
  }
  constructor(private el: ElementRef) { }
} 

处理程序将自动删除ngOnDestroy.

其他解决方案请参阅:

• 如何在Angular中的Document对象上侦听mousemove事件

Answer 2

这应该解决问题:

import { Directive, ElementRef, OnDestroy } from "@angular/core";

@Directive({
    selector: "[Enter]"
})
export class Enter implements OnDestroy{
    private enter;
    constructor(el: ElementRef) {
        this.enter = function(event){
            if(event.keyCode === 13){
                el.nativeElement.click();
                console.log("enter triggered");
            }
        }
        document.addEventListener('keyup', this.enter , false);
        console.log("Added event listener");
    }

    ngOnDestroy(){
        document.removeEventListener('keyup', this.enter, false);
        console.log("Removed event listener"); 
    }
}

希望这可以帮助.

干杯,深圳

Answer 3

让它像这样：

import { Directive, ElementRef, OnDestroy } from "@angular/core";

@Directive({
    selector: "[Enter]"
})
export class Enter implements OnDestroy{

    private enter: (event: KeyboardEvent) => void;

    constructor(el: ElementRef) {
        this.enter = (event) => {
            if(event.keyCode === 13){
                el.nativeElement.click();
            }
        }
        document.addEventListener('keyup',  this.enter , false);
    }

    ngOnDestroy(){
        document.removeEventListener('keyup', this.enter, false);
    }
}