import { HttpClient } from '@angular/common/http'; import { Pipe, PipeTransform } from '@angular/core'; @Pipe({ name: 'fetch', pure: false }) export class FetchJsonPipe implements PipeTransform { private cachedData: any = null; private cachedUrl = ''; constructor(private http: HttpClient) { } transform(url: string): any { if (url !== this.cachedUrl) { this.cachedData = null; this.cachedUrl = url; this.http.get(url).subscribe(result => this.cachedData = result); } return this.cachedData; } }