With this code we can see that we have access to the entire form (output, which comes to us as a JavaScript error alort, below).
<?php
function formmsgs_image_style_name($form, $form_state) {
die(var_export($form,TRUE));
}
?>Crucially, it also gives us the value that has been entered into the (unsubmitted) form. Here, that is 'head shot'.
An AJAX HTTP error occurred. HTTP Result Code: 200 Debugging information follows. Path: /system/ajax StatusText: OK ResponseText: array ( 'name' => array ( '#type' => 'textfield', '#size' => '64', '#title' => 'Style name', '#default_value' => '', '#description' => 'The name is used in URLs for generated images. Use only lowercase alphanumeric characters, underscores (_), and hyphens (-).', '#element_validate' => array ( 0 => 'image_style_name_validate', ), '#required' => true, '#ajax' => array ( 'callback' => 'formmsgs_image_style_name', 'event' => 'keyup', 'wrapper' => 'formmsgs-image-style-name', ), '#suffix' => 'Default message.', '#input' => true, '#maxlength' => 128, '#autocomplete_path' => false, '#process' => array ( 0 => 'ajax_process_form', ), '#theme' => 'textfield', '#theme_wrappers' => array ( 0 => 'form_element', ), '#defaults_loaded' => true, '#tree' => false, '#parents' => array ( 0 => 'name', ), '#array_parents' => array ( 0 => 'name', ), '#weight' => 0, '#processed' => true, '#attributes' => array ( ), '#title_display' => 'before', '#id' => 'edit-name--2', '#name' => 'name', '#value' => 'head shot', '#needs_validation' => true, '#ajax_processed' => true, '#attached' => array ( 'library' => array ( 0 => array ( 0 => 'system', 1 => 'jquery.form', ), 1 => array ( 0 => 'system', 1 => 'drupal.ajax', ), ), 'js' => array ( 0 => array ( 'type' => 'setting', 'data' => array ( 'ajax' => array ( 'edit-name--2' => array ( 'callback' => 'formmsgs_image_style_name', 'event' => 'keyup', 'wrapper' => 'formmsgs-image-style-name', 'url' => '/system/ajax', 'submit' => array ( '_triggering_element_name' => 'name', ), ), ), ), ), ), ), '#sorted' => true, ), 'submit' => array ( '#type' => 'submit', '#value' => 'Create new style', '#input' => true, '#name' => 'op', '#button_type' => 'submit', '#executes_submit_callback' => true, '#limit_validation_errors' => false, '#process' => array ( 0 => 'ajax_process_form', ), '#theme_wrappers' => array ( 0 => 'button', ), '#defaults_loaded' => true, '#tree' => false, '#parents' => array ( 0 => 'submit', ), '#array_parents' => array ( 0 => 'submit', ), '#weight' => 0.001, '#processed' => true, '#required' => false, '#attributes' => array ( ), '#title_display' => 'before', '#id' => 'edit-submit--2', '#ajax_processed' => false, '#sorted' => true, ), '#form_id' => 'image_style_add_form', '#build_id' => 'form-AOQK0kh-ZfbkPMEFdRVcLmPB3kgqjtf19rypnqYajkQ', '#action' => '/admin/config/media/image-styles/add', '#type' => 'form', 'form_build_id' => array ( '#type' => 'hidden', '#value' => 'form-AOQK0kh-ZfbkPMEFdRVcLmPB3kgqjtf19rypnqYajkQ', '#id' => 'form-AOQK0kh-ZfbkPMEFdRVcLmPB3kgqjtf19rypnqYajkQ', '#name' => 'form_build_id', '#input' => true, '#process' => array ( 0 => 'ajax_process_form', ), '#theme' => 'hidden', '#defaults_loaded' => true, '#tree' => false, '#parents' => array ( 0 => 'form_build_id', ), '#array_parents' => array ( 0 => 'form_build_id', ), '#weight' => 0.002, '#processed' => true, '#required' => false, '#attributes' => array ( ), '#title_display' => 'before', '#ajax_processed' => false, '#sorted' => true, ), '#token' => 'image_style_add_form', 'form_token' => array ( '#id' => 'edit-image-style-add-form-form-token', '#type' => 'token', '#default_value' => 'pWL1C-vAdfinCfYuAF4zM_cH3cX_rPM0GuJzQzXZML4', '#input' => true, '#theme' => 'hidden', '#defaults_loaded' => true, '#tree' => false, '#parents' => array ( 0 => 'form_token', ), '#array_parents' => array ( 0 => 'form_token', ), '#weight' => 0.003, '#processed' => false, '#required' => false, '#attributes' => array ( ), '#title_display' => 'before', '#name' => 'form_token', '#value' => 'pWL1C-vAdfinCfYuAF4zM_cH3cX_rPM0GuJzQzXZML4', '#needs_validation' => true, '#sorted' => true, ), 'form_id' => array ( '#type' => 'hidden', '#value' => 'image_style_add_form', '#id' => 'edit-image-style-add-form', '#input' => true, '#process' => array ( 0 => 'ajax_process_form', ), '#theme' => 'hidden', '#defaults_loaded' => true, '#tree' => false, '#parents' => array ( 0 => 'form_id', ), '#array_parents' => array ( 0 => 'form_id', ), '#weight' => 0.004, '#processed' => true, '#required' => false, '#attributes' => array ( ), '#title_display' => 'before', '#name' => 'form_id', '#ajax_processed' => false, '#sorted' => true, ), '#id' => 'image-style-add-form--2', '#method' => 'post', '#theme_wrappers' => array ( 0 => 'form', ), '#tree' => false, '#parents' => array ( ), '#submit' => array ( 0 => 'image_style_add_form_submit', ), '#theme' => array ( 0 => 'image_style_add_form', ), '#processed' => false, '#defaults_loaded' => true, '#required' => false, '#attributes' => array ( ), '#title_display' => 'before', '#array_parents' => array ( ), '#sorted' => true, )