filepload.ts

public updateAvatar(file: File): Observable<any> {
    return Observable.create((observer) => {
      let formData: FormData = new FormData(),
          xhr: XMLHttpRequest = new XMLHttpRequest();


      formData.append('avatar', file, file.name);

      xhr.onreadystatechange = () => {
        if (xhr.readyState === 4) {
          if (xhr.status === 200) {
            observer.next(JSON.parse(xhr.response));
            observer.complete();
          } else {
            observer.error(JSON.parse(xhr.response));
            observer.complete();
          }
        }
      };

      xhr.open('POST', ApiUrlHelper.apiV1Url + '/user/updateAvatar', true);
      xhr.setRequestHeader('Authorization', 'Bearer ' + localStorage.getItem('id_token'));
      xhr.send(formData);
    });
  }