app/common/directives/loader.js

window.angular && (function (angular) {
    'use strict';

    angular
        .module('app.common.directives')
        .directive('loader', function () {
            return {
                'restrict': 'E',
                'templateUrl': 'common/directives/loader.html',
                scope: {
                    loading: '='
                }
            };
        });

})(window.angular);