bg2.directive.ts

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

@Directive({
    selector: '[app-ch-color]'
})
export class bgDirective{
    constructor(private el: ElementRef, private renderer: Renderer){
        this.changeColor('red');
    }
    @HostBinding('style.border') border : string;
    @HostListener('click') koo(){
      this.border = '5px solid yellow';
    }
    changeColor(color: string){
        this.renderer.setElementStyle(this.el.nativeElement, 'color', color);  
    }
}