<div class="panel">

<div id="tree" class="tree">
<ul>
<?php
foreach($courses as $course_row)
{
?>
        <li><a class="course" id="<?=$course_row->course_id?>" href="#"><?echo $course_row->course_title?></a>
        <ul>
<?      foreach($section_to_course as $row_StC)
        {
            if($course_row->course_id == $row_StC->course_id)
            {
                foreach($sections as $section_row)
                    if($section_row->section_id == $row_StC->section_id)
                    {
?>
                        <li><a class="section" id="<?=$section_row->section_id?>" href="#"><?echo $section_row->section_title?></a>
                        <ul>
<?                      foreach($test_to_section as $row_TtS)
                        {
                            if($section_row->section_id == $row_TtS->section_id)
                            {
                                foreach($tests as $test_row)
                                    if($test_row->test_id == $row_TtS->test_id)
                                    {
?>
                                    <li><a class="test" id="<?=$test_row->test_id?>" href="#"><?echo $test_row->test_title?></a>
                                    </li>
<?                      
                                    }
                            }
                        }
?>
                        </ul>
                        </li>
                        
<?
                    }
            }
        }
?>
        </ul>
        </li>
<?
}
?> 
</ul>
</div>

<div id="content">www</div>

</div>

script type="text/javascript" class="source">
    $(function () {
	$("#tree")
    .jstree({ 
		"plugins" : [ "themes", "html_data", "ui", "crrm", "contextmenu", "dnd", "hotkeys", "json_data" ]
	})
    
    $('.course').click(function(){
            var id_course = $(this).attr('id');
            $('#content').html('course \'s content, ID_course = ' + id_course);
            //return false;
        })
    $('.section').click(function(){
            var id_section = $(this).attr('id');
            var id_course = $(this).parents("ul").parent('li').find('a:[id]').attr('id');
            $('#content').html('section \'s content, ID_section = '+ id_section + ' ID_course = ' + id_course);
            //return false;
        })
    $('.test').click(function(){
            var id_test = $(this).attr('id');
            var id_section = $(this).parents("ul").parent('li').find('a:[id]').attr('id');
            //$('#content').html('course \'s content');
            $('#content').html('test \'s content, ID_test = ' + id_test + ' ID_section = ' + id_section);
            //return false;
        })     
    });
</script>

$('some_element').closest('parents_element').attr('id');
$('some_element').parents('parents_element').attr('id');
$('some_element').parent().attr('id');