promise.ts

Promise<Article[]> articles = this.http.get('api.learn-angular.fr/articles')
                                      .toPromise()
                                      .then((res: Response) => res.json() as Article[])
                                      .catch(this.handleError);

...

private handleError(error: any): Promise<any> {
    console.error('Une erreur est survenue : ', error); 
    return Promise.reject(error.message || error);
}