I've a custom callback with a form which works well in last chrome and last FF.
$form['foo']['bar'] = array( '#type' => 'submit', '#value' => t(''), '#attributes' => ['class' => array('search-api glyphicon glyphicon-refresh btn-primary')], '#ajax' => [ 'callback' => '::fetchApiData', 'event' => 'click', 'effect' => 'none', 'progress' => [ 'type' => 'throbber', 'message' => NULL, ], ], );
However, my customer has a old version of firefox, the esr 45.9.0 version, and when we click on the button that trigger the callback, we have an alert error.
An error occurred while attempting to process /declaration?ajax_form=1&_wrapper_format=drupal_ajax: invalid regular expression flag a
Does anybody know how to debug this?