Download several files from Firebase Storage through an Angular8 application in zip format

Angular FireStore zip download

// dependencies
// angular 8
// "firebase": "^7.6.1",
// "file-saver": "^2.0.2",
// "jszip": "^3.2.2"

file-download.entity.ts

export class FileDownloadEntity {

  name: string;
  fileName: string;
  extension: string;

  constructor(name: string, fileName: string, extension: string) {
    this.name = name;
    this.fileName = fileName;
    this.extension = extension;
  }
}

storage.service.ts

import {Injectable} from '@angular/core';
import {AngularFireStorage} from '@angular/fire/storage';
import {HttpClient} from '@angular/common/http';
import {saveAs} from 'file-saver/dist/FileSaver';
import {FileDownloadEntity} from 'file-download.entity';
import * as JSZip from 'jszip';

@Injectable()
export class StorageService {

  constructor(private angularFireStorage: AngularFireStorage,
              private httpClient: HttpClient) {
  }

  public downloadZippedFiles(files: FileDownloadEntity[], zipName: string): void {

    const zipFile: JSZip = new JSZip();
    let count = 0;

    files.forEach(file => {
      this.angularFireStorage.ref('/' + file.name).getDownloadURL().subscribe(url => {
        this.httpClient.get(url, {responseType: 'blob'}).subscribe(response => {

          zipFile.file(file.fileName + file.extension, response, {binary: true});

          count++;
          if (count === files.length) {
            zipFile.generateAsync({type: 'blob'}).then(content => {
              saveAs(content, zipName + '.zip');
            });
          }
        });
      });
    });
  }
}