APINotices is an AngularJS module that displays a "working" and "error" div during AJAX requests.

api_notices.js

angular.module('ApiNotice', []).
  config(function ($httpProvider)
  {
    $httpProvider.responseInterceptors.push('myHttpInterceptor');
    var spinnerFunction = function (data, headersGetter)
    {
      // todo start the spinner here
      $('#api-error').hide();
      $('#api-access').show();
      return data;
    };

    $httpProvider.defaults.transformRequest.push(spinnerFunction);
  }).

// register the interceptor as a service, intercepts ALL angular ajax http calls
  factory('myHttpInterceptor', function ($q, $window) {
        return function (promise) {
            return promise.then(function (response) {
                // do something on success
                // todo hide the spinner
                $('#api-access').hide();
                return response;

            }, function (response) {
                window.resp = response;
                if( response.status == 422 )
                {
                  $('#api-error .message').html('Errors:');
                  errors = [];
                  if( window.resp.data && window.resp.data.errors )
                  {
                    errors = window.resp.data.errors;
                  }
                  else if( window.resp.data )
                  {
                    errors = window.resp.data;
                  }

                  $.each(errors, function(a, b) { $('#api-error .message').append("<li>" + a + " " + b + "</li>");});
                }
                // do something on error
                // todo hide the spinner
                $('#api-access').hide();
                $('#api-error').show();
                return $q.reject(response);
            });
        };
    })