Making all REST Server calls to Drupal site as an authenticated user through Services
You can use jdrupal.min.js. and set variables as follows in your js:

 Drupal.settings.site_path = "http://example.com"; // SET Drupal site Path  
 Drupal.settings.endpoint = "services_endpoint_name";  // Set the Service Resource REST endpoint path FROM services module in Drupal site.


and you can use directly functions for for doing operation such as:

user_login(username, password, {
                        success: function (result) {
                          cosole.log(result);
                        },
                        error: function (xhr, status, message) {
                            console.log(status +" Error Message"+ message)
                        }
                    });


If login successful then you are logged in with the authenticated user in your Drupal site. And also you can do number of operations node save, update, delete etc.