浅析Angular中的自定义结构型/属性型指令

<div *ngIf=""></div>
<!-- 等价于 -->
<ng-template [ngIf]="">
  <div></div>
</ng-template>

@Directive({
  selector: '[appLogin]'
})
export class LoginDirective implements OnInit{
  @Input('appLogin') user=""
  constructor(private VCR: ViewContainerRef,private TPL: TemplateRef<any>) { 
  //在指令的构造函数中将 TemplateRef 和 ViewContainerRef 注入成私有变量。
  }
  ngOnInit(){
    if(this.user=='superadmin'||this.user=="admin"){
      this.VCR.createEmbeddedView(this.TPL)
    }else{
      this.VCR.clear()
    }
  }
}

<div *appLogin="'superadmin'">超级管理员</div>
<div *appLogin="'admin'">管理员</div>
<div *appLogin="'user'">普通会员</div>

@Directive({
  selector: '[appColor]'
})
export class ColorDirective implements OnInit{
  @Input() appColor=""
  constructor(private ele:ElementRef) { 
    
  }
  ngOnInit(){
    if (this.appColor == 'superadmin'){
      this.ele.nativeElement.style.backgroundColor="red"
    } else if (this.appColor == 'admin') {
      this.ele.nativeElement.style.backgroundColor = "green"
    }else{
      this.ele.nativeElement.style.backgroundColor = "blue"
    }
  }
}

<div [appColor]="'superadmin'">超级管理员</div>
<div [appColor]="'admin'">管理员</div>
<div [appColor]="'user'">普通会员</div>**