AngularJS: Custom maxlength and minlength with surrogate pair support.(1.2.x)

directive.js

angular.module('directive')
    .directive("spMaxlength", function() {
        return {
            restrict: 'A',
            require: 'ngModel',
            link: function(scope, elm, attrs, ctrl) {
                var max = parseInt(attrs.spMaxlength || 0, 10);
                ctrl.$parsers.unshift(function(viewValue) {
                    var len = viewValue ? viewValue.length - (viewValue.match(/[\uD800-\uDBFF][\uDC00-\uDFFF]/g)||[]).length : 0;
                    if (len <= max) {
                        ctrl.$setValidity("maxlength", true);
                        return viewValue;
                    } else {
                        ctrl.$setValidity("maxlength", false);
                        return undefined;
                    }
                });
            }
        };
    })
    .directive("spMinlength", function() {
        return {
            restrict: 'A',
            require: 'ngModel',
            link: function(scope, elm, attrs, ctrl) {
                var min = parseInt(attrs.spMinlength || 0, 10);
                ctrl.$parsers.unshift(function(viewValue) {
                    var len = viewValue ? viewValue.length - (viewValue.match(/[\uD800-\uDBFF][\uDC00-\uDFFF]/g)||[]).length : 0;
                    if (len == 0 || len >= min) {
                        ctrl.$setValidity("minlength", true);
                        return viewValue;
                    } else {
                        ctrl.$setValidity("minlength", false);
                        return undefined;
                    }
                });
            }
        };
    });