Passing multivaluearray from php to javascript after ajax call
I searched on the wrong position, after i found:
http://www.thecarneyeffect.co.uk/drupal-8-ajax
I got the solution here
https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Ajax%21SettingsCommand.php/class/SettingsCommand/8.2.x

use Drupal\Core\Ajax\AjaxResponse;
use Drupal\Core\Ajax\SettingsCommand;

function ajaxCallback(array &amp;$form, FormStateInterface $form_state) {

    $form_state-&gt;setRebuild();

    $myValue = $form_state-&gt;getValue('myValue');

    $ajax_response = new AjaxResponse();
    $ajax_response-&gt;addCommand(new SettingsCommand([
       'variable' =&gt; $myValue,
    ], TRUE));

  return $ajax_response;
}