I have develop many custom form and added ajax functionality with the form field, Ajax code works like a charm with my custom form.

But now i have a situation where i have add ajax callback to the title field of node.

For this i am using hook_form_alter, and adding same ajax code to title, but ajax event is not firing up for title field.

below is my code:

function module_form_FORM_ID_alter(&$  form, FormStateInterface $  form_state, $  form_id){    $  form['title']['#ajax'] = [     'callback' => 'module_updateCategoryDropDown',     'event' => 'change',     'progress' => [       'type' => 'throbber',       'message' => t('Verifying...'),      ],  ]; }  function module_updateCategoryDropDown(array &$  form, FormStateInterface $  form_state){   /* form category dropdown code is here */ }