Connecting with a remote server via XHR and handling connection errors

gistfile1.js

        function authenticate(callback, error) {
            resetErrors();
            angular.element('#login-form input[type=submit]').button('loading');
            
            $scope.authRequest = new XMLHttpRequest();
            $scope.authRequest.open('GET', 'http://lfo-prtg:81/odata/', true, 'UNRWA\\' + $scope.username, $scope.password);
            $scope.authRequest.send();
            $scope.connectionTimer = $interval(function () {
                $scope.authRequest.abort();
                
                $scope.errorConnection = true;
                angular.element('#login-form input[type=submit]').button('reset');
            }, 2500);
            $scope.authRequest.onError = function () {
                $scope.errorHttp = true;
                angular.element('#login-form input[type=submit]').button('reset');
            };
            $scope.authRequest.onload = function () {
                angular.element('#login-form input[type=submit]').button('reset');
                $interval.cancel($scope.connectionTimer);
                
                if (this.status >= 200 && this.status < 400) {
                    resetErrors();
                    callback();
                } else if (this.status >= 401 && this.status <= 403) {
                    $scope.errorAuth = true;
                } else {
                    $scope.errorServer = true;
                }
            };
        }