How i use js alert on my option from dropdown when ever i select any value and will get value in alert box

Yii 1.1 General Discussion
1

$criteria = new CDbCriteria;

                           $course_names =CHtml::listData(NasfiaWorkTypes::model()->findAll($criteria),'id','name'); 
				     $course_list = CMap::mergeArray(array(0=>Yii::t('app','Select Work Type')),$course_names);
				     $course=$_GET['id'];
				
                     echo CHtml::dropDownList('course','',$course_list,array(
                    'ajax' => array(
                    'type'=>'POST',
                    'url'=>CController::createUrl('/hr/staff/SetAttendance'),
                    'update'=>'#id',
                    'data'=>'js:{name:$(this).val(), "'.Yii::app()->request->csrfTokenName.'":"'.Yii::app()->request->csrfToken.'"}',),'style'=>'width:150px;','options' => array($course=>array('selected'=>true),)));
            
                     ?></td>