AngularJS Decimal Only Directive

currency.js

angular.module('myApp.directives', []).directive('currency', function () {
        return {
            restrict: 'A',
            transclude: false,
            require: '^ngModel',
            scope: false,
            controller: function ($scope, $element, $attrs) {
                $scope.$watch($attrs.ngModel, function (newValue, oldValue) {
                    var val = newValue.toString().replace(/[^\d.-]/g, '');
                    val = val.length > 0 ? val : '""';
                    while (val.split(".").length - 1 > 1)
                        val = val.replace('.', '');
                    while (val.split("-").length - 1 > 1)
                        val = val.replace('-', '');
                    switch (val.substr(val.length - 1)) {
                        case '.':
                            val = '"' + val + '"';
                            break;
                        case '-':
                            val = '"' + val + '"';
                            break;
                        case '0':
                            val = '"' + val + '"';
                            break;
                    }
                    eval('$scope.' + $attrs.ngModel + ' = ' + val + '');
 
                });
            }
        };
    });