date_picker
Github

    public function date_picker()
    {
        return _class('html')->date_picker('input_name', '2015-02-02');
    }
    public function date_picker($name, $cur_date = '')
    {
        js('jquery-ui');
        css('jquery-ui');

        jquery('$(".datepicker").datepicker({ dateFormat: "yy-mm-dd" });');
        css('//cdnjs.cloudflare.com/ajax/libs/jqueryui/1.10.4/css/jquery.ui.datepicker.min.css');

        $extra['id'] = $extra['id'] ?: __FUNCTION__ . '_' . ++$this->_ids[__FUNCTION__];
        // TODO: use input() unified control
        return '<input type="text" name="' . $name . '" class="datepicker" value="' . $cur_date . '" style="width:80px" readonly="true" id="' . $extra['id'] . '" />';
    }