如何在angularjs中从datapicker验证日期

Question

这是我的datepicker指令

app.directive("datepicker2", function() {
    return {
        restrict: "A",
        require: "ngModel",
        link: function(scope, elem, attrs, ngModelCtrl) {
            var updateModel = function(dateText) {
                scope.$apply(function() {
                    ngModelCtrl.$setViewValue(dateText);
                });
            };
            var regionalOptions = {
                "regional": [{
                    "es": {
                        closeText: "Cerrar",
                        prevText: "<Ant",
                        nextText: "Sig>",
                        currentText: "Hoy",
                        monthNames: ["enero", "febrero", "marzo", "abril", "mayo", "junio",
                            "julio", "agosto", "septiembre", "octubre", "noviembre", "diciembre"
                        ],
                        monthNamesShort: ["ene", "feb", "mar", "abr", "may", "jun",
                            "jul", "ago", "sep", "oct", "nov", "dic"
                        ],
                        dayNames: ["domingo", "lunes", "martes", "miércoles", "jueves", "viernes", "sábado"],
                        dayNamesShort: ["dom", "lun", "mar", "mié", "jue", "vie", "sáb"],
                        dayNamesMin: ["D", "L", "M", "X", "J", "V", "S"],
                        weekHeader: "Sm",
                        dateFormat: "dd/mm/yy",
                        firstDay: 1,
                        isRTL: false,
                        showMonthAfterYear: false,
                        yearSuffix: ""
                    }
                }]
            };

            var options = {
                     changeMonth: true,
                      changeYear: true,
                      yearRange: "1900:2300",
                      buttonImage: "calendar.gif",

            };

            elem.datepicker(options);
            elem.datepicker(angular.copy(regionalOptions));
        }
    }

});

JSP： -

<input type="text" id="datepicker" datepicker2 ng-change="hindeDateOfBirth()">

如何验证年龄应超过6个月的年龄。即今天（2017年5月22日）。如果我选择1月也不应该允许。如果是11月那么它应该接受。