app.directive("regExInput", function () {
   "use strict";
    return {
    restrict: "A",
    require: "?regEx",
    scope: {},
    replace: false,
    link: function (scope, element, attrs, ctrl) {
      element.bind('keypress', function (event) {
        var regex = new RegExp(attrs.regEx);
        var key = String.fromCharCode(!event.charCode ? event.which : event.charCode);
        if (!regex.test(key)) {
            event.preventDefault();
            return false;
        }
      });
    }
   };
});