AngularJS Lowercase Directive that will force the input to be lowercased

gistfile1.js

_module.directive('lowercase', function () {
    return {
        require: 'ngModel',
        link: function ($scope, elem, attrs, ngModelCtrl) {
            var lowercase = function (inputValue) {
                if(inputValue == undefined) inputValue = '';

                var lowercased = inputValue.toLowerCase();

                if(lowercased !== inputValue) {
                    ngModelCtrl.$setViewValue(lowercased);
                    ngModelCtrl.$render();
                }

                return lowercased;
            }

            ngModelCtrl.$parsers.unshift(lowercase);
            lowercase($scope[attrs.ngModel]);
        }
    };
});