angular-docs-cn/public/docs/_examples/pipes/ts/app/flying-heroes.pipe.ts

/* tslint:disable use-pipe-transform-interface */
// #docregion
// #docregion pure
import { Pipe, PipeTransform } from '@angular/core';

import { Flyer } from './heroes';

@Pipe({ name: 'flyingHeroes' })
export class FlyingHeroesPipe implements PipeTransform {
  transform(allHeroes: Flyer[]) {
    // #docregion filter
    return allHeroes.filter(hero => hero.canFly);
    // #enddocregion filter
  }
}
// #enddocregion pure

/////// Identical except for the pure flag
// #docregion impure
// #docregion pipe-decorator
@Pipe({
  name: 'flyingHeroesImpure',
  pure: false
})
// #enddocregion pipe-decorator
export class FlyingHeroesImpurePipe extends FlyingHeroesPipe {}
// #enddocregion impure