<?php
require MODX_BASE_PATH . 'ActionsHandler.php'; // Подключаем наш класс
$handler = new ActionsHandler($modx);
if ($response = $handler->handle()) {
    echo $response; // Отдаем наш ответ браузеру
    exit();
}

protected function helloAction() {
    return $this->success('Hello message', ['hello' => 'Hello, World!']);
}

			$("a.settings-list__sort-item").click(function(e){
				e.preventDefault();
				var href = $(this).attr("href");
				
				$.ajax({
				    url:'ajax',
				    type:'GET',
				    data: href,
				    success: function(data){ // при успехе
							$('.listing').html( data );
						},
						error: function(){ // при неудаче
							$('.listing').html('Ошибка! Попробуйте ещё раз!');
						}
				})
			}); 

switch($_GET['q']){     
        case 'ajax':
				/* START */
				
				$docid = 5;
				$p['extenders'] = 'request';
				$p['andFilterTv'] = "";

				$p['parents'] = $docid;
				$p['tpl'] = 'cat.tpl';
				$p['display'] = '12';
				$p['depth'] = 1;
				$p['sortDir'] = (isset($_GET['ditto_sortDir']))? $_SESSION['sortDir'] = $_GET['ditto_sortDir'] : (isset($_SESSION['sortDir']) )? $_SESSION['sortDir'] : 'DESC';
				$p['sortBy'] = (isset($_GET['ditto_sortBy']))? $_SESSION['sortBy'] = $_GET['ditto_sortBy'] : (isset($_SESSION['sortBy']) )? $_SESSION['sortBy'] : 'pub_date';
				$p['truncLen'] = 70;
				$p['paginate'] = 1;
				$p['hideFolders'] = 1;
				$p['showInMenuOnly'] = 0;
				$p['tplPaginatePrevious']='@CODE:<a href="[+url+]"><</a>';
				$p['tplPaginateNext']='@CODE:<a href="[+url+]">></a>';
				$p['tplPaginateCurrentPage']='@CODE:<span class="active">[+page+]</span>';
				$p['debug'] = 0;

				$html = $modx->runSnippet('Ditto', $p);
				echo $html;

				/* END */
        break;
}
die();

GET http://mag/ajax?/?ditto_sortBy=price&dateSource=price&ditto_sortDir=ASC 500 (Internal Server Error)

$('.pager a').on('click', function(e) {
				//var href = $(this).attr("href");
				var text = $(this).text(); 
		    $.ajax({
				    url:'/run.html',
				    type:'GET',
				    data: { start: text },
				    success: function(data){ // при успехе
							$('.listing').html( data );
						}
				});
		    e.preventDefault();
		  });