Добавление разрыва страницы в многоступенчатую форму

Я думаю, вам следует прикрепить свою пользовательскую функцию предварительного загрузчика ajax к форме следующим образом:

$form['#attached']['js'] = array(
  array(
    'type'  => 'file',
    'data' => drupal_get_path('module', 'MY_MODULE') . '/js/ajax_preloader.js',
  ),
);

Ajax_preloader.js

(function($) {
  Drupal.behaviors.events = {
    attach: function(context, settings) {
      $('#steps-form', context).ajaxStart(function() {
        // ...
      });
      $('#steps-form', context).ajaxSuccess(function() {
        // ...   
      });
    }
  };
})(jQuery);

В качестве альтернативы вы можете создать свою собственную команду (пример Mypreloaderexample)

(function($, Drupal) {
  Drupal.ajax.prototype.commands.myPreloaderExample = function(ajax, response, status) {
    $('#steps-form').ajaxStart(function() {
      //...
    });
    $('#steps-form').ajaxSuccess(function() {
      // ...
    });
  };
}(jQuery, Drupal));

Я не уверен, какова ваша цель, но если вы собираетесь создать многоступенчатую форму ajax со следующими функциями:

• Показывать только текущий элемент формы
• Сохранить все ранее предоставленные значения (разрешить предварительный просмотр всех значений не теряя их)

Вы можете создать такую форму следующим образом:

/**
 * An example of steps form.
 */
function steps_form($form, &$form_state) {

  // Because we have many fields with the same values, we have to set
  // #tree to be able to access them.
  $form['#tree'] = TRUE;

  $form['steps_fieldset'] = array(
    '#type' => 'fieldset',
    '#title' => t('Steps form'),
    // Set up the wrapper so that AJAX will be able to replace the fieldset.
    '#prefix' => '<div id="steps-fieldset-wrapper">',
    '#suffix' => '</div>',
  );

  $form['steps_fieldset']['actions'] = array(
    '#type' => 'actions'
  );

  // Build the fieldset with the proper number of steps.
  // Use $form_state['step'] to determine the number of textfields to build.
  if (empty($form_state['step'])) {
    $form_state['step'] = 1;
  }

  // An array with form values.
  if (empty($form_state['storage'])) {
    $form_state['storage'] = array();
  }

  // Define the number of steps.
  $form_state['steps_number'] = 3;

  // build all textfields with steps
  for ($i = 0; $i < $form_state['step']; $i++) {

    // set the type of each previous form item as a hidden. Only last step will be shown.
    $type = ($i == ($form_state['step']-1)) ? 'textfield' : 'hidden';

    // get the default value of step.
    $default_value = isset($form_state['storage'][$i]) ?  $form_state['storage'][$i] : '';  

    $form['steps_fieldset']['step'][$i] = array(
      '#type' => $type,
      '#title' => t('Step') . ' ' . ($i+1),
      '#required' => FALSE,
      '#default_value' => $default_value,
    );
  }

  // The next step button.
  if ($form_state['step'] != $form_state['steps_number']) {
    $form['steps_fieldset']['actions']['add_step'] = array(
      '#type' => 'submit',
      '#weight' => '1',
      '#value' => t('Next step'),
      '#submit' => array('steps_form_add_one'),
      '#ajax' => array(
        'callback' => 'steps_form_callback',
        'wrapper' => 'steps-fieldset-wrapper',
      ),
    );
  }

  // The previous step button.  
  if ($form_state['step'] > 1) {
    $form['steps_fieldset']['actions']['remove_step'] = array(
      '#type' => 'submit',
      '#weight' => '0',
      '#value' => t('Previous step'),
      '#submit' => array('steps_form_remove_one'),
      '#ajax' => array(
        'callback' => 'steps_form_callback',
        'wrapper' => 'steps-fieldset-wrapper',
      ),
    );
  }

  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Submit'),
  );

  $form['#attached']['js'] = array(
    array(
      'type'  => 'file',
      'data' => drupal_get_path('module', 'MY_MODULE') . '/js/ajax_preloader.js',
    ),
  );
  return $form;
}

/**
 * Callback for both ajax-enabled buttons.
 *
 * Selects and returns the fieldset with all values in it.
 */
function steps_form_callback($form, $form_state) {

  $commands = array();
  // return the form
  $commands[] = ajax_command_html('#steps-fieldset-wrapper', render($form['steps_fieldset']));
  // add your custom ajax command
  $commands[] = array(
    'command' => 'myPreloaderExample',
    // define some custom variables if you need to
    'someValue' => 'some value',
  );

  return array('#type' => 'ajax', '#commands' => $commands);
}

/**
 * Submit handler for the "add-one-more" button.
 *
 * - save the form value, so the user will be able to preview all previously provided values without loosing them.
 * - increments the step counter.
 * - rebuild the form.
 */
function steps_form_add_one($form, &$form_state) {

  $form_state['storage'][$form_state['step']-1] = $form_state['input']['steps_fieldset']['step'][$form_state['step']-1];
  if ($form_state['step'] < $form_state['steps_number']) {
    $form_state['step']++;
  }
  $form_state['rebuild'] = TRUE;
}

/**
 * Submit handler for the "remove one" button.
 *
 * Decrements the step counter and causes a form rebuild.
 */
function steps_form_remove_one($form, &$form_state) {
  if ($form_state['step'] > 1) {
    $form_state['step']--;
  }
  $form_state['rebuild'] = TRUE;
}

/**
 * Final submit handler.
 *
 * Reports what values were finally set.
 */
function steps_form_submit($form, &$form_state) {
  $output = t('All my values: @steps',
    array('@steps' => implode(', ', $form_state['values']['steps_fieldset']['step'])) );
  drupal_set_message($output);
}

Результаты