Removing EventListener in ngOnDestroy
<p>I have the following implementation of a directive. How to removeEventListener in this case:</p>

<pre><code>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!
    }
}
</code></pre>

<p>I know I can simply use a global variable here and can access it. But I don't want to store the state of instance in the global variable.</p>