Angular cents directive for validation

ns-cents.js

/**
 * Created by tyler on 5/1/14.
 */

(function(){

    'use strict';

    angular.module('fsApp')
        .directive('nsCents', [function () {
            return {
                restrict: 'A',
                require : 'ngModel',
                link: function postLink(scope, element, attrs, ctrl) {

                    ctrl.$parsers.unshift(
                        function(viewValue) {
                            if(!_.isUndefined(viewValue) && viewValue !== ''){
                                // remove spaces and commas and dollar sign
                                var _r = viewValue.toString().replace(/\s|,|\$/g, '');

                                if(_r.length && _r[0] === '.'){
                                    _r = '0' + _r;
                                }

                                var _rs = _r.split('.');

                                var _f = parseInt(_rs[0]);
                                var _s = 0;

                                if(_rs.length > 1){
                                    if(_rs[1].length === 1){
                                        _rs[1] += '0';
                                    }
                                    _s = parseInt(_rs[1].toString().substring(0, 2));
                                }

                                var _n = (_f * 100) + _s;

                                if(!isNaN(_n)){
                                    ctrl.$setValidity('nsCents', true);
                                    return _n;
                                } else {
                                    ctrl.$setValidity('nsCents', false);
                                    return undefined;
                                }
                            } else {
                                ctrl.$setValidity('nsCents', true);
                                return undefined;
                            }
                        }
                    );

                    ctrl.$formatters.unshift(function(modelValue){
                        if(!_.isUndefined(modelValue)){
                            return (modelValue/100).toFixed(2);
                        } else {
                            return undefined;
                        }
                    });
                }
            };
        }]);

}());