angular-docs-cn/public/docs/_examples/testing/ts/app/shared/highlight.directive.ts

// #docregion
import { Directive, ElementRef, Input, OnChanges, Renderer } from '@angular/core';

@Directive({ selector: '[highlight]' })
/** Set backgroundColor for the attached element to highlight color
 *  and set the element's customProperty to true */
export class HighlightDirective implements OnChanges {

  defaultColor =  'rgb(211, 211, 211)'; // lightgray

  @Input('highlight') bgColor: string;

  constructor(private renderer: Renderer, private el: ElementRef) {
    renderer.setElementProperty(el.nativeElement, 'customProperty', true);
  }

  ngOnChanges() {
    this.renderer.setElementStyle(
      this.el.nativeElement, 'backgroundColor',
      this.bgColor || this.defaultColor );
  }
}