Шаблон файла с обработкой ajax данных.

ajax.php

<?php
require($_SERVER["DOCUMENT_ROOT"] . "/bitrix/modules/main/include/prolog_before.php");

if ((empty($_SERVER["HTTP_X_REQUESTED_WITH"]) || strtolower($_SERVER["HTTP_X_REQUESTED_WITH"]) != "xmlhttprequest") OR !check_bitrix_sessid()) {
    CHTTP::SetStatus('401 Unauthorized');
    die("Unauthorized");
}

header('Content-Type: application/json');
$response = ['ERROR' => 'OK'];









if (!empty($response['ERROR'])) {
    CHTTP::SetStatus('400 Bad Request');
}

echo json_encode($response);
require($_SERVER["DOCUMENT_ROOT"]."/bitrix/modules/main/include/epilog_after.php");