Using a directive to add class to host element [duplicate]

Answer 1

Why would you want to use the Renderer or Renderer2 class? The preferred way to do this in a directive is to use the @HostBinding decorator.

Example:

import { HostBinding } from '@angular/core';

@Directive({
    selector: '[myDirective]'
})
export class MyDirective {

    @HostBinding('class')
    className = 'my-directive-css-class';
}