title: How to extend Renderer2 in Angular 11?
body: <p>I need to implement <code>removeAllClasses()</code> and <code>addClasses(string[])</code> methods by extending Renderer2.</p>
  <pre><code>import { Injectable, Renderer2 } from '@angular/core';
  @Injectable({
    providedIn: 'root'
  })
  export abstract class RendererExtended extends Renderer2 (
    protected constructor() {
      super();
    }
  
    public removeAllClasses(el: any) {
      this.removeAttribute(el, 'class');
    }
  }
  </code></pre>
  <p>And when I try to use it in component:</p>
  <pre><code>constructor(
   private renderer: RendererExtended) {
  }
  
  private showOrHideArrow() {
    this.renderer.removeAllClasses(this.iconComponentRef.location.nativeElement);
    this.renderer.addClass(this.iconComponentRef.location.nativeElement, 'hovered');
  }
    
  </code></pre>
  <p>I see an error:
  <code>ERROR TypeError: _this.renderer.addClass is not a function</code></p>