Knockout jQuery Button Binding Handler

gistfile1.js

if (ko && ko.bindingHandlers) {
    ko.bindingHandlers['jEnable'] = {
        'update': function(element, valueAccessor) {
            var value = ko.utils.unwrapObservable(valueAccessor());
            var $element = $(element);
            $element.prop("disabled", !value);

            if ($element.hasClass("ui-button")) {
                $element.button("option", "disabled", !value);
            }
        }
    };
}