javascript - Angular 2中的属性指令@Input别名

Question

我正在学习 Angular 2 中的属性指令。在属性指令中使用 @Input 别名时，它不起作用，为什么？

组件

<p appHighlight = "color">Hightlight Me</p>

指令

export class HighlightDirective {

  @Input('appHighlight') highlightcolor: string;

  constructor(
    // ElementRef is a service that grants direct access to the DOM element through its nativeElement property.
    private el: ElementRef
  ) {
    // el.nativeElement.style.backgroundColor = 'yellow';
  }


  // @HostListener decorator lets you subscribe to events of the DOM element that hosts an attribute directive
  @HostListener('mouseenter') onMouseEnter() {
    this.highlight(this.highlightcolor || 'red');
  }

  @HostListener('mouseleave') onmouseleave() {
    this.highlight(null);
  };

  private highlight(color: string) {
    this.el.nativeElement.style.backgroundColor = color;
  }

}

Answer 1

符号应该是这样的:

<p myHighlight [appHighlight]="color">Hightlight Me</p>

用括号

假设选择器是:

@Directive({
  selector: '[myHighlight]'
})
export class HighlightDirective {

  constructor(private el: ElementRef) { }

  @Input('appHighlight') highlightcolor: string;
  ...

Plunker 示例:http://plnkr.co/edit/vqZ4gjHc1KNFro62HlVJ?p=preview