Disable weekends on a jQuery Tools DateInput

gistfile1.js

var dateinput = $('input[type="date"]').dateinput({
    "onShow": function(event) {
        var calendar = this.getCalendar();
        var conf = this.getConf();
        var classes = conf.css.off + ' ' + conf.css.disabled;
        function disableWeekends() {
            var weeks = calendar.find('.calweek');
            weeks.find('a:first, a:last').addClass(classes);
        }
        calendar.find('#calprev, #calnext').click(disableWeekends);
        disableWeekends();
    }
});