TOPIC:

function ff_Customer_action(element, action)
{
    switch (action) {
        case 'change':
            jQuery.ajax({
                type: "POST",
                
                url: "<?php return JURI::root(true ); ?>/Select_list_Customer_Model.php",
                data: { code: ff_getElementByName('Customer').value},    
                success: function(data) {
                var obj = JSON.parse(data);
                var result = [];

    var keys = Object.keys(obj);
    keys.forEach(function(key){
        result.push(obj[key]);

    });
                        jQuery('#ff_elem370').empty();
                       
                       jQuery('#ff_elem370').append(jQuery('<option>', {
                                value: '',
                                text: 'Choose option'
                            }));
                       for (var i = 0; i < result.length; i++) { 
                           console.log(result[i]);
                           jQuery('#ff_elem370').append(jQuery('<option>', {
                                value: result[i],
                                text: result[i]
                            })); 
                        }
                }      
            });
            break;
        default:;
    } // switch
} // ff_Customer_action

<?php

define('_JEXEC', 1);
if (file_exists(__DIR__ . '/defines.php'))
{
    include_once _DIR_ . '/defines.php';
}
if (!defined('_JDEFINES'))
{
    define('JPATH_BASE', __DIR__);
    require_once JPATH_BASE . '/includes/defines.php';
}
require_once JPATH_BASE . '/includes/framework.php';


$db = JFactory::getDBO(); 

$code=$_POST['code']; // the value posted from the AJAX request above

$db = JFactory::getDBO();

$db->setQuery("Select Model From jos_Projects Where Customer = '$code' ");


$row =$db->loadColumn();
 if(!$row){
 	echo "error";
} else {

	echo json_encode($row);
}

?>

for(var i=0;i<result.length;i++){

var rezz=result[i];

jQuery('#ff_elem410').append(jQuery('<option>',{value:rezz[1],text:rezz[0]}));