http-interceptor.service.ts

public interceptBefore(request: InterceptedRequest): InterceptedRequest {
    this.blockUI.load();
    var token = this.auth.getToken();
    if(token) {
      request.options.headers.set('x-access-token',token);
    }
    return request;
}

public interceptAfter(response): InterceptedResponse {
    this.blockUI.stop();
    var jsonResponse = response.response.json();
    if(response.response.ok === false) {
      var message = jsonResponse.message;
      this.snackBar.open(message, 'Error', {duration: 5000});
    }
    if(response.response.status === 401) {
      this.auth.logout();
    }
    return response;
}