Angular 9-指令，如何从组件读取属性

import { Directive, ElementRef, Input } from '@angular/core';

@Directive({
  selector: '[appExample]'
})
export class ExampleDirective {
  @Input('appExample') customProperty: any;

  constructor(private el: ElementRef) { }

  ngOnChanges() {
    // 在这里，您可以根据 customProperty 的值改变 DOM ，或者执行其他操作
    this.el.nativeElement.style.backgroundColor = this.customProperty;
  }
}

<!-- app.component.html -->
<div [appExample]="propertyValue">Custom property value is: {{ propertyValue }}</div>

// app.component.ts
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})
export class AppComponent {
  propertyValue = 'red';
}