<?= yii\jui\DatePicker::widget(['name' => 'attributeName', 'clientOptions' => ['defaultDate' => '2014-01-01']]) ?>

<?php

use yii\jui\Dialog;

Dialog::begin([

    'clientOptions' => [

        'modal' => true,

    ],

]);

 

echo 'Dialog contents here...';

 

Dialog::end();

?>