//组件
export class AppComponent {
  title = 'my-App';
  msg = 'yqq';
}

//自定义管道
import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'lcUppercase'
})
export class LcUppercasePipe implements PipeTransform {

  transform(value: string, ...args :string[]): string {
    if(value == 'yqq'){
       return value.toUpperCase()+'大帅哥';
    }
   return 'yyds';
  }
}

/*视图*/
<h1>{{msg|lcUppercase}}</h1>