diff -u b/ajax_example/ajax_example.links.menu.yml b/ajax_example/ajax_example.links.menu.yml
--- b/ajax_example/ajax_example.links.menu.yml
+++ b/ajax_example/ajax_example.links.menu.yml
@@ -4,60 +4,70 @@
-  parent: ''
-
+   weight: 10
 ajax_example.simplest:
   title: 'Simplest AJAX Example'
   route_name: 'ajax_example.simplest'
-  parent: ''
+  parent: ajax_example.description
 
 ajax_example.autocheckboxes:
   title: 'Generate checkboxes'
   route_name: 'ajax_example.autocheckboxes'
+  parent: ajax_example.description
 
 ajax_example.autotextfeilds:
   title: 'Generate textfields'
   route_name: 'ajax_example.autotextfields'
+  parent: ajax_example.description
 
 ajax_example.submit-driven:
   title: 'Submit-driven AJAX'
   route_name: 'ajax_example.submit-driven-ajax'
+  parent: ajax_example.description
 
 ajax_example.dependent-dropdown:
   title: 'Dependent dropdown'
   route_name: 'ajax_example.dependent_dropdown'
+  parent: ajax_example.description
 
 ajax_example.dependent-dropdown-degardes:
   title: 'Dependent dropdown degardes'
   route_name: 'ajax_example.dependent_dropdown_degardes'
+  parent: ajax_example.description
 
 ajax_example.dependent-dropdown-degardes-nojava:
   title: 'Dependent dropdown degardes w/JS turned off '
   route_name: 'ajax_example.dependent_dropdown_degardes_nojava'
+  parent: ajax_example.description
 
 ajax_example.dynamic-dropdown:
   title: 'Dynamic Sections (with graceful degradation)'
   route_name: 'ajax_example.dynamic_sections'
+  parent: ajax_example.description
 
 ajax_example.dynamic-dropdown-degardes-nojava-example:
   title: 'Dynamic Sections (with graceful degradation) w/js turned off'
   route_name: 'ajax_example.dynamic_sections_nojava'
+  parent: ajax_example.description
 
 ajax_example.wizard-example:
-  title: 'Ajax Wizard Example'
+  title: 'AJAX Wizard Example'
   route_name: 'ajax_example.Wizard'
+  parent: ajax_example.description
 
 ajax_example.wizard-examplenojs:
-  title: 'Ajax Wizard Example w/JS turned off'
+  title: 'AJAX Wizard Example w/JS turned off'
   route_name: 'ajax_example.Wizardnojs'
+  parent: ajax_example.description
 
 ajax_example.addmorenojs:
   title: 'Add more button (with graceful degradation) w/JS turned off'
   route_name: 'ajax_example.Addmorenojs'
+  parent: ajax_example.description
 
 ajax_example.addmore:
-  title: 'Ajax Add more button'
+  title: 'AJAX Add more button'
   route_name: 'ajax_example.Addmore'
+  parent: ajax_example.description
 
 ajax_example.Advanced:
   title: 'AJAX framework commands'
   route_name: 'ajax_example.Advanced'
-
-
+  parent: ajax_example.description
reverted:
--- b/ajax_example/config/install/ajaxexample.settings.yml
+++ /dev/null
@@ -1 +0,0 @@
-variable_name : 0
diff -u b/ajax_example/css/ajax_example.css b/ajax_example/css/ajax_example.css
--- b/ajax_example/css/ajax_example.css
+++ b/ajax_example/css/ajax_example.css
@@ -2,7 +2,6 @@
  * @file
  * CSS for ajax_example.
  *
- * See @link ajax_example_dependent_dropdown_degrades @endlink for
  * details on what this file does. It is not used in any other example.
  */
 /* Hides the next button when not degrading to non-javascript browser */
diff -u b/ajax_example/js/ajax_example.js b/ajax_example/js/ajax_example.js
--- b/ajax_example/js/ajax_example.js
+++ b/ajax_example/js/ajax_example.js
@@ -2,8 +2,6 @@
  * @file
  * JavaScript for ajax_example.
  *
- * See @link ajax_example_dependent_dropdown_degrades @endlink for
- * details on what this file does. It is not used in any other example.
  */
 
 (function($) {
diff -u b/ajax_example/src/Controller/AjaxExampleController.php b/ajax_example/src/Controller/AjaxExampleController.php
--- b/ajax_example/src/Controller/AjaxExampleController.php
+++ b/ajax_example/src/Controller/AjaxExampleController.php
@@ -9,15 +9,15 @@
 use Drupal\Core\Url;
 use Drupal\Core\Ajax\AppendCommand;
 use Drupal\Core\Database\Database;
-use Drupal\Core\Database\Query\Condition;
+use Drupal\Core\Database\Connection;
 use Drupal\Component\Utility\SafeMarkup;
 
-
 /**
- * Controller routines for block example routes.
+ * Controller routines for AJAX example routes.
  */
 class AjaxExampleController extends ControllerBase {
   use DescriptionTemplateTrait;
+  protected $connection;
 
   /**
    * {@inheritdoc}
@@ -27,6 +27,17 @@
   }
 
   /**
+   *
+   */
+
+  public function basicInstructions() {
+    return [
+      $this->description(),
+    ];
+  }
+
+
+  /**
    * Get the progress bar execution status, as JSON.
    *
    * This is the menu handler for
@@ -81,7 +92,8 @@
   public function ajaxExampleRenderLinkRa() {
 
     $build['my_div'] = [
-      '#markup' => $this->t('The link below has been rendered as an element with the #ajax property, so if
+      '#markup' => $this->t('
+The link below has been rendered as an element with the #ajax property, so if
 javascript is enabled, ajax.js will try to submit it via an AJAX call instead
 of a normal page load. The URL also contains the "/nojs/" magic string, which
 is stripped if javascript is enabled, allowing the server code to tell by the
@@ -138,7 +150,6 @@
    *   If $type == 'ajax', returns an array of AJAX Commands.
    *   Otherwise, just returns the content, which will end up being a page.
    *
-   * @ingroup ajax_example
    */
   public function ajaxlinkresponse($type = 'ajax') {
     if ($type == 'ajax') {
@@ -159,77 +170,104 @@
   }
 
-  public function ajax_example_simple_user_autocomplete_callback($string = "") {
-
-  $matches = array();
-
-  if ($string) {
-    $db = \Drupal::database();
-    $result = $db->select('users')
-      ->fields('users', array('name', 'uid'))
-      ->condition('name', $db->like($string) . '%', 'LIKE')
-      ->range(0, 10)
-      ->execute();
-    foreach ($result as $user) {
-      // In the simplest case (see user_autocomplete), the key and the value are
-      // the same. Here we'll display the uid along with the username in the
-      // dropdown.
-      $matches[] = array('value' => $user->name, 'label' => $user->uid);
-      $matches[$user->name] = SafeMarkup::check_plain($user->name) . " (uid=$user->uid)";
+/**
+   * It works simply by searching usernames (and of course in Drupal usernames
+   * are unique, so can be used for identifying a record.)
+   *
+   * The returned $matches array has
+   * * key: string which will be displayed once the autocomplete is selected
+   * * value: the value which will is displayed in the autocomplete pulldown.
+   *
+   * In the simplest cases (see drupal/ajax_example/form/AjaxExampleAutocomplete.php)
+   * these are the same, andnothing needs to be done. However, more complicated
+   * autocompletes require more work. Here we demonstrate the difference by
+   * displaying the UID along with the username in the dropdown.
+   *
+   * In the end, though, we'll be doing something with the value that ends up in
+   * the textfield, so it needs to uniquely identify the record we want to access.
+   * This is demonstrated in ajax_example_unique_autocomplete().
+   *
+   * @param string $string
+   *   The string that will be searched.
+   */
+  public function ajax_example_simple_user_autocomplete_callback(Connection $connection, $string = "") {
+    $this->connection = Connection::$connection;
+    $matches = [];
+
+    if ($string) {
+
+      $result = $this->connection->select('users')
+        ->fields('users', ['name', 'uid'])
+        ->condition('name', $this->connection->like($string) . '%', 'LIKE')
+        ->range(0, 10)
+        ->execute();
+      foreach ($result as $user) {
+        // In the simplest case (see user_autocomplete), the key and the value are
+        // the same. Here we'll display the uid along with the username in the
+        // dropdown.
+        $matches[] = ['value' => $user->name, 'label' => $user->uid];
+        $matches[$user->name] = SafeMarkup::check_plain($user->name) . " (uid=$user->uid)";
+      }
     }
+
+    return new JsonResponse($matches);
   }
 
-  return new JsonResponse($matches);
-}
-/**
- * Autocomplete callback for nodes by title.
- *
- * Searches for a node by title, but then identifies it by nid, so the actual
- * returned value can be used later by the form.
- *
- * The returned $matches array has
- * - key: The title, with the identifying nid in brackets, like "Some node
- *   title [3325]"
- * - value: the title which will is displayed in the autocomplete pulldown.
- *
- * Note that we must use a key style that can be parsed successfully and
- * unambiguously. For example, if we might have node titles that could have
- * [3325] in them, then we'd have to use a more restrictive token.
- *
- * @param string $string
- *   The string that will be searched.
- */
-public function ajax_example_unique_node_autocomplete_callback($string = "") {
-  $matches = array();
-  if ($string) {
-    $db = Database::getConnection();
-    $result = $db->select('node')
-      ->fields('node', array('nid', 'title'))
-      ->condition('title', $db->escapeLike($string) . '%', 'LIKE')
-      ->range(0, 10)
-      ->execute();
-    foreach ($result as $node) {
-      $matches[$node->title . " [$node->nid]"] = SafeMarkup::check_plain($node->title);
+  /**
+   * Autocomplete callback for nodes by title.
+   *
+   * Searches for a node by title, but then identifies it by nid, so the actual
+   * returned value can be used later by the form.
+   *
+   * The returned $matches array has
+   * - key: The title, with the identifying nid in brackets, like "Some node
+   *   title [3325]"
+   * - value: the title which will is displayed in the autocomplete pulldown.
+   *
+   * Note that we must use a key style that can be parsed successfully and
+   * unambiguously. For example, if we might have node titles that could have
+   * [3325] in them, then we'd have to use a more restrictive token.
+   *
+   * @param string $string
+   *   The string that will be searched.
+   */
+  public function ajax_example_unique_node_autocomplete_callback($string = "") {
+    $this->connection = Connection::$connection;
+    $matches = [];
+    if ($string) {
+
+      $result = $this->connection->select('node')
+        ->fields('node', ['nid', 'title'])
+        ->condition('title', $this->connection->escapeLike($string) . '%', 'LIKE')
+        ->range(0, 10)
+        ->execute();
+      foreach ($result as $node) {
+        $matches[$node->title . " [$node->nid]"] = SafeMarkup::check_plain($node->title);
+      }
     }
+
+    return new JsonResponse($matches);
   }
 
-  return new JsonResponse($matches);
-}
-public function ajax_example_node_by_author_node_autocomplete_callback($author_uid, $string = "") {
-  $matches = array();
-  if ($author_uid > 0 && trim($string)) {
-    $db = Database::getConnection();
-    $result = $db->select('node')
-      ->fields('node', array('nid', 'title'))
-      ->condition('uid', $author_uid)
-      ->condition('title', $db->escapeLike($string) . '%', 'LIKE')
-      ->range(0, 10)
-      ->execute();
-    foreach ($result as $node) {
-      $matches[$node->title . " [$node->nid]"] = SafeMarkup::check_plain($node->title);
+  /**
+   *
+   */
+  public function ajax_example_node_by_author_node_autocomplete_callback($author_uid, $string = "") {
+    $this->connection = Connection::$connection;
+    $matches = [];
+    if ($author_uid > 0 && trim($string)) {
+      $db = Database::getConnection();
+      $result = $db->select('node')
+        ->fields('node', ['nid', 'title'])
+        ->condition('uid', $author_uid)
+        ->condition('title', $db->escapeLike($string) . '%', 'LIKE')
+        ->range(0, 10)
+        ->execute();
+      foreach ($result as $node) {
+        $matches[$node->title . " [$node->nid]"] = SafeMarkup::check_plain($node->title);
+      }
     }
-  }
 
-  return new JsonResponse($matches);
-}
+    return new JsonResponse($matches);
+  }
 
 }
diff -u b/ajax_example/src/Form/AjaxExampleAddMore.php b/ajax_example/src/Form/AjaxExampleAddMore.php
--- b/ajax_example/src/Form/AjaxExampleAddMore.php
+++ b/ajax_example/src/Form/AjaxExampleAddMore.php
@@ -20,7 +20,8 @@
   }
 
   /**
-   * {@inheritdoc}
+   * This example shows a button to "add more" - add another textfield, and
+   * the corresponding "remove" button.
    */
   public function buildForm(array $form, FormStateInterface $form_state, $no_js_use = FALSE) {
     $url = Url::fromUri('internal:/examples/ajax-example/add-more-nojs/');
@@ -30,7 +31,7 @@
     $urltwo = Url::fromUri('internal:/examples/ajax_example/add-more');
     $linktwo = Link::fromTextAndUrl($this->t('AJAX version'), $urltwo)->toString();
     $form['description'] = [
-      '#markup' =>t('This example shows an add-more and a remove-last button. The @link does it without page reloads; the @link2 is the same code but simulates a non-javascript environment, showing it with page reloads.',
+      '#markup' => t('This example shows an add-more and a remove-last button. The @link does it without page reloads; the @link2 is the same code but simulates a non-javascript environment, showing it with page reloads.',
       ['@link' => $linktwo, '@link2' => $link]),
 
     ];
@@ -62,8 +63,6 @@
       '#type' => 'submit',
       '#value' => t('Add one more'),
       '#submit' => ['::ajax_example_add_more_add_one'],
-    // See the examples in ajax_example.module for more details on the
-    // properties of #ajax.
       '#ajax' => [
         'callback' => '::prompt',
         'wrapper' => 'names-fieldset-wrapper',
@@ -149,7 +148,6 @@
       );
+    // Sets a message to display to the user.
     drupal_set_message($output);
   }
 
-
-
 }
diff -u b/ajax_example/src/Form/AjaxExampleAdvancedCommands.php b/ajax_example/src/Form/AjaxExampleAdvancedCommands.php
--- b/ajax_example/src/Form/AjaxExampleAdvancedCommands.php
+++ b/ajax_example/src/Form/AjaxExampleAdvancedCommands.php
@@ -4,19 +4,29 @@
 
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\Core\Ajax;
 use Drupal\Core\Ajax\AjaxResponse;
 use Drupal\Core\Ajax\ReplaceCommand;
 use Drupal\Core\Ajax\HtmlCommand;
 use Drupal\Core\Ajax\AlertCommand;
 use Drupal\Core\Ajax\AppendCommand;
 use Drupal\Core\Ajax\BeforeCommand;
+use Drupal\Core\Ajax\AddCssCommand;
 use Drupal\Core\Ajax\AfterCommand;
 use Drupal\Core\Ajax\ChangedCommand;
 use Drupal\Core\Ajax\DataCommand;
 use Drupal\Core\Ajax\PrependCommand;
 use Drupal\Core\Ajax\RemoveCommand;
 use Drupal\Core\Ajax\RestripeCommand;
+
+/**
+ * @file
+ * AJAX Commands examples.
+ *
+ * This demonstrates each of the
+ * new AJAX commands. This is consolidated into a dense page because
+ * it's advanced material and because it would spread itself all over creation
+ * otherwise.
+ */
 /**
  *
  */
@@ -30,7 +40,7 @@
   }
 
   /**
-   * {@inheritdoc}
+   * Form to display the AJAX Commands.
    */
   public function buildForm(array $form, FormStateInterface $form_state) {
     $form = [];
@@ -213,7 +223,7 @@
     $form['restripe_command_example_fieldset']['restripe_num_rows'] = [
       '#type' => 'select',
       '#default_value' => !empty($form_state->getValue('restripe_num_rows')) ? $form_state->getValue('restripe_num_rows') : 1,
-      '#options' => [1 => 1, 2 => 2, 3 => 3, 4 => 4, 5 => 5,  6 => 6, 7 => 7, 8 => 8, 9 => 9, 10 => 10],
+      '#options' => [1 => 1, 2 => 2, 3 => 3, 4 => 4, 5 => 5, 6 => 6, 7 => 7, 8 => 8, 9 => 9, 10 => 10],
       '#ajax' => [
         'callback' => '::ajax_example_advanced_commands_restripe_num_rows',
         'method' => 'replace',
@@ -246,187 +256,184 @@
+  /**
+   * Callback for 'after'.
+   *
+   * @see Drupal\Core\Ajax\AfterCommand;
+   */
+  public function ajax_example_advanced_commands_after_callback($form, $form_state) {
+    $selector = '#after_div';
+    $response = new AjaxResponse();
+    $response->addCommand(new AfterCommand($selector, "New 'after'..."));
+    $response->addCommand(new ReplaceCommand("#after_status", "Updated after_command_example" . date('r') . ""));
+    return $response;
+  }
 
+  /**
+   * Callback for 'alert'.
+   *
+   * @see Drupal\Core\Ajax\AlertCommand;
+   */
+  public function ajax_example_advanced_commands_alert_callback($form, $form_state) {
+    $response = new AjaxResponse();
+    $response->addCommand(new AlertCommand("Alert requested at " . date('r')));
+    return $response;
+  }
 
-/**
- * Callback for 'after'.
- *
- * @see ajax_command_after()
- */
-public function ajax_example_advanced_commands_after_callback($form, $form_state) {
-  $selector = '#after_div';
-  $response = new AjaxResponse();
-  $response->addCommand( new AfterCommand($selector, "New 'after'..."));
-  $response->addCommand( new ReplaceCommand("#after_status", "Updated after_command_example".date('r').""));
-  return $response;
-}
-
-/**
- * Callback for 'alert'.
- *
- * @see ajax_command_alert()
- */
-public function ajax_example_advanced_commands_alert_callback($form, $form_state) {
-  $response = new AjaxResponse();
-  $response->addCommand( new AlertCommand("Alert requested at " . date('r')));
-  return $response;
-}
-
-/**
- * Callback for 'append'.
- *
- * @see ajax_command_append()
- */
-public function ajax_example_advanced_commands_append_callback($form, $form_state) {
-  $selector = '#append_div';
-  $response = new AjaxResponse();
-  $response->addCommand( new AppendCommand($selector, "Stuff..."));
-  $response->addCommand( new ReplaceCommand("#append_status", "<div id='append_status'>Updated append_command_example " . date('r') . "</div>"));
-  return $response;
-}
-
-/**
- * Callback for 'before'.
- *
- * @see ajax_command_before()
- */
-public function ajax_example_advanced_commands_before_callback($form, $form_state) {
-  $selector = '#before_div';
-  $response = new AjaxResponse();
-  $response->addCommand( new BeforeCommand($selector, "New 'before'..."));
-  $response->addCommand( new ReplaceCommand("#before_status", "<div id='before_status'>Updated before_command_example " . date('r') . "</div>"));
+  /**
+   * Callback for 'append'.
+   *
+   * @see Drupal\Core\Ajax\AppendCommand;
+   */
+  public function ajax_example_advanced_commands_append_callback($form, $form_state) {
+    $selector = '#append_div';
+    $response = new AjaxResponse();
+    $response->addCommand(new AppendCommand($selector, "Stuff..."));
+    $response->addCommand(new ReplaceCommand("#append_status", "<div id='append_status'>Updated append_command_example " . date('r') . "</div>"));
+    return $response;
+  }
 
-  return $response;
-}
+  /**
+   * Callback for 'before'.
+   *
+   * @see Drupal\Core\Ajax\BeforeCommand;
+   */
+  public function ajax_example_advanced_commands_before_callback($form, $form_state) {
+    $selector = '#before_div';
+    $response = new AjaxResponse();
+    $response->addCommand(new BeforeCommand($selector, "New 'before'..."));
+    $response->addCommand(new ReplaceCommand("#before_status", "<div id='before_status'>Updated before_command_example " . date('r') . "</div>"));
 
-/**
- * Callback for 'changed'.
- *
- * @see ajax_command_changed()
- */
-public function ajax_example_advanced_commands_changed_callback($form, $form_state) {
-  $checkbox_value = $form_state->getValue('changed_command_example');
-  $checkbox_value_string = $checkbox_value ? "TRUE" : "FALSE";
-  $response = new AjaxResponse();
-  if ($checkbox_value) {
-    $response->addCommand( new ChangedCommand('#changed_div', '#changed_div_mark_this'));
-  }
-  else {
-    $response->addCommand(new ReplaceCommand('#changed_div', "<div id='changed_div'> <div id='changed_div_mark_this'>This div can be marked as changed or not.</div></div>"));
+    return $response;
   }
-  $response->addCommand( new ReplaceCommand("#changed_status", "<div id='changed_status'>Updated changed_command_example to $checkbox_value_string: " . date('r') . "</div>"));
+
+  /**
+   * Callback for 'changed'.
+   *
+   * @see Drupal\Core\Ajax\ChangedCommand;
+   */
+  public function ajax_example_advanced_commands_changed_callback($form, $form_state) {
+    $checkbox_value = $form_state->getValue('changed_command_example');
+    $checkbox_value_string = $checkbox_value ? "TRUE" : "FALSE";
+    $response = new AjaxResponse();
+    if ($checkbox_value) {
+      $response->addCommand(new ChangedCommand('#changed_div', '#changed_div_mark_this'));
+    }
+    else {
+      $response->addCommand(new ReplaceCommand('#changed_div', "<div id='changed_div'> <div id='changed_div_mark_this'>This div can be marked as changed or not.</div></div>"));
+    }
+    $response->addCommand(new ReplaceCommand("#changed_status", "<div id='changed_status'>Updated changed_command_example to $checkbox_value_string: " . date('r') . "</div>"));
     return $response;
-}
+  }
 
-/**
- * Callback for 'css'.
- *
- * @see ajax_command_css()
- */
-public function ajax_example_advanced_commands_css_callback($form, $form_state) {
-  $selector = '#css_div';
-  $color = $form_state->getValue('css_command_example');
-  $response = new AjaxResponse();
-  $response->addCommand(new CssCommand($selector, ['background-color' => $color]));
-  $response->addCommand(new ReplaceCommand("#css_status", "<div id='css_status'>Updated css_command_example to '{$color}' " . date('r') . "</div>"));
-  return $response;
-}
+  /**
+   * Callback for 'css'.
+   *
+   * @see Drupal\Core\Ajax\AddCssCommand;
+   */
+  public function ajax_example_advanced_commands_css_callback($form, $form_state) {
+    $selector = '#css_div';
+    $color = $form_state->getValue('css_command_example');
+    $response = new AjaxResponse();
+    $response->addCommand(new AddCssCommand($selector, ['background-color' => $color]));
+    $response->addCommand(new ReplaceCommand("#css_status", "<div id='css_status'>Updated css_command_example to '{$color}' " . date('r') . "</div>"));
+    return $response;
+  }
 
-/**
- * Callback for 'data'.
- *
- * @see ajax_command_data()
- */
-public function ajax_example_advanced_commands_data_callback($form, $form_state) {
-  $selector = '#data_div';
-  $text = $form_state->getValue('data_command_example');
-  list($key, $value) = preg_split('/=/', $text);
-
-  $response = new AjaxResponse();
-  $response->addCommand(new DataCommand($selector, $key, $value));
-  $response->addCommand(new ReplaceCommand("#data_status", "<div id='data_status'>Updated data_command_example with key=$key, value=$value; " . date('r') . "</div>"));
-  return $response;
-}
+  /**
+   * Callback for 'data'.
+   *
+   * @see Drupal\Core\Ajax\DataCommand
+   */
+  public function ajax_example_advanced_commands_data_callback($form, $form_state) {
+    $selector = '#data_div';
+    $text = $form_state->getValue('data_command_example');
+    list($key, $value) = preg_split('/=/', $text);
+
+    $response = new AjaxResponse();
+    $response->addCommand(new DataCommand($selector, $key, $value));
+    $response->addCommand(new ReplaceCommand("#data_status", "<div id='data_status'>Updated data_command_example with key=$key, value=$value; " . date('r') . "</div>"));
+    return $response;
+  }
 
-/**
- * Callback for 'html'.
- *
- * @see ajax_command_html()
- */
-public function ajax_example_advanced_commands_html_callback($form, $form_state) {
-  $text = $form_state->getValue('html_command_example');
-  $response = new AjaxResponse();
-  $response->addCommand(new HtmlCommand('#html_div', $text));
-  $response->addCommand(new ReplaceCommand("#html_status", "<div id='html_status'>Updated html_command_example with text=$text;  " . date('r') . "</div>"));
-  return $response;
-}
+  /**
+   * Callback for 'html'.
+   *
+   * @see Drupal\Core\Ajax\HtmlCommand
+   */
+  public function ajax_example_advanced_commands_html_callback($form, $form_state) {
+    $text = $form_state->getValue('html_command_example');
+    $response = new AjaxResponse();
+    $response->addCommand(new HtmlCommand('#html_div', $text));
+    $response->addCommand(new ReplaceCommand("#html_status", "<div id='html_status'>Updated html_command_example with text=$text;  " . date('r') . "</div>"));
+    return $response;
+  }
 
-/**
- * Callback for 'prepend'.
- *
- * @see ajax_command_prepend()
- */
-public function ajax_example_advanced_commands_prepend_callback($form, $form_state) {
-  $response = new AjaxResponse();
-  $response->addCommand(new PrependCommand('#prepend_div', "Prepended Stuff..."));
-  $response->addCommand(new ReplaceCommand("#prepend_status", "<div id='prepend_status'>Updated prepend_command_example " . date('r') . "</div>"));
+  /**
+   * Callback for 'prepend'.
+   *
+   * @see Drupal\Core\Ajax\PrependCommand
+   */
+  public function ajax_example_advanced_commands_prepend_callback($form, $form_state) {
+    $response = new AjaxResponse();
+    $response->addCommand(new PrependCommand('#prepend_div', "Prepended Stuff..."));
+    $response->addCommand(new ReplaceCommand("#prepend_status", "<div id='prepend_status'>Updated prepend_command_example " . date('r') . "</div>"));
 
-  return $response;
-}
+    return $response;
+  }
 
-/**
- * Callback for 'remove'.
- *
- * @see ajax_command_remove()
- */
-public function ajax_example_advanced_commands_remove_callback($form, $form_state) {
-  $response = new AjaxResponse();
-  $should_remove = $form_state->getValue('remove_command_example');
-  $should_remove_string = $should_remove ? 'TRUE' : 'FALSE';
-  if ($should_remove) {
-    $response->addCommand(new RemoveCommand('#remove_text'));
+  /**
+   * Callback for 'remove'.
+   *
+   * @see Drupal\Core\Ajax\RemoveCommand
+   */
+  public function ajax_example_advanced_commands_remove_callback($form, $form_state) {
+    $response = new AjaxResponse();
+    $should_remove = $form_state->getValue('remove_command_example');
+    $should_remove_string = $should_remove ? 'TRUE' : 'FALSE';
+    if ($should_remove) {
+      $response->addCommand(new RemoveCommand('#remove_text'));
 
-  }
-  else {
-    $response->addCommand(new HtmlCommand('#remove_div', "<div id='remove_text'>text to be removed</div>"));
     }
-  $response->addCommand(new ReplaceCommand("#remove_status", "<div id='remove_status'>Updated remove_command_example (value={$should_remove_string} " . date('r') . "</div>"));
+    else {
+      $response->addCommand(new HtmlCommand('#remove_div', "<div id='remove_text'>text to be removed</div>"));
+    }
+    $response->addCommand(new ReplaceCommand("#remove_status", "<div id='remove_status'>Updated remove_command_example (value={$should_remove_string} " . date('r') . "</div>"));
 
     return $response;
 
-}
+  }
 
-/**
- * Callback for 'restripe'.
- *
- * Rebuilds the table with the selected number of rows.
- */
-public function ajax_example_advanced_commands_restripe_num_rows($form, $form_state) {
-  $num_rows = $form_state->getValue('restripe_num_rows');
-  $output = "<table id='restripe_table' style='border: 1px solid black'>";
-  for ($i = 1; $i <= $num_rows; $i++) {
-    $output .= "<tr><td>Row $i</td></tr>";
+  /**
+   * Callback for 'restripe'.
+   *
+   * Rebuilds the table with the selected number of rows.
+   */
+  public function ajax_example_advanced_commands_restripe_num_rows($form, $form_state) {
+    $num_rows = $form_state->getValue('restripe_num_rows');
+    $output = "<table id='restripe_table' style='border: 1px solid black'>";
+    for ($i = 1; $i <= $num_rows; $i++) {
+      $output .= "<tr><td>Row $i</td></tr>";
+    }
+    $output .= "</table>";
+    return $output;
   }
-  $output .= "</table>";
-  return $output;
-}
 
-/**
- * Callback for 'restripe'.
- *
- * @see ajax_command_restripe()
- */
-public function ajax_example_advanced_commands_restripe_callback($form, $form_state) {
-  $response = new AjaxResponse();
-  $response->addCommand(new RestripeCommand('#restripe_table'));
-  $response->addCommand(new ReplaceCommand("#restripe_status", "<div id='restripe_status'>Restriped table " . date('r') . "</div>"));
+  /**
+   * Callback for 'restripe'.
+   *
+   * @see Drupal\Core\Ajax\RestripeCommand
+   */
+  public function ajax_example_advanced_commands_restripe_callback($form, $form_state) {
+    $response = new AjaxResponse();
+    $response->addCommand(new RestripeCommand('#restripe_table'));
+    $response->addCommand(new ReplaceCommand("#restripe_status", "<div id='restripe_status'>Restriped table " . date('r') . "</div>"));
 
-  return $response;
+    return $response;
 
-}
+  }
 
-/**
- *
- */
-public function submitForm(array &$form, FormStateInterface $form_state) {
-}
+  /**
+   *
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+  }
 
 }
-
diff -u b/ajax_example/src/Form/AjaxExampleAutocheckboxes.php b/ajax_example/src/Form/AjaxExampleAutocheckboxes.php
--- b/ajax_example/src/Form/AjaxExampleAutocheckboxes.php
+++ b/ajax_example/src/Form/AjaxExampleAutocheckboxes.php
@@ -6,7 +6,7 @@
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- *
+ * Generate a changing number of checkboxes.
  */
 class AjaxExampleAutocheckboxes extends FormBase {
 
@@ -76,8 +76,17 @@
   }
 
   /**
-   * Handles switching the available regions based on the selected theme.
-   */
+ * Callback for autocheckboxes.
+ *
+ * Callback element needs only select the portion of the form to be updated.
+ * Since #ajax['callback'] return can be HTML or a renderable array (or an
+ * array of commands), we can just return a piece of the form.
+ * See @link examples/ajax-example/advanced-commands for more details
+ * on AJAX framework commands.
+ *
+ * @return array
+ *   Renderable array (the checkboxes fieldset)
+ */
   public function prompt($form, FormStateInterface $form_state) {
     return $form['checkboxes_fieldset'];
   }
diff -u b/ajax_example/src/Form/AjaxExampleAutocomplete.php b/ajax_example/src/Form/AjaxExampleAutocomplete.php
--- b/ajax_example/src/Form/AjaxExampleAutocomplete.php
+++ b/ajax_example/src/Form/AjaxExampleAutocomplete.php
@@ -6,7 +6,7 @@
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- *
+ * A simple autocomplete form which just looks up usernames in the user table.
  */
 class AjaxExampleAutocomplete extends FormBase {
 
@@ -36,7 +36,7 @@
   }
 
   /**
-   *
+   * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
   }
diff -u b/ajax_example/src/Form/AjaxExampleAutocompleteAuthor.php b/ajax_example/src/Form/AjaxExampleAutocompleteAuthor.php
--- b/ajax_example/src/Form/AjaxExampleAutocompleteAuthor.php
+++ b/ajax_example/src/Form/AjaxExampleAutocompleteAuthor.php
@@ -14,44 +14,44 @@
  */
 class AjaxExampleAutocompleteAuthor extends FormBase {
 
-  /**
-   * {@inheritdoc}
-   */
-  public function getFormID() {
-    return 'ajax_example_autocompleteauthor';
-  }
+/**
+ * {@inheritdoc}
+ */
+public function getFormID() {
+  return 'ajax_example_autocompleteauthor';
+}
 
-  /**
-   * {@inheritdoc}
-   */
-  public function buildForm(array $form, FormStateInterface $form_state) {
-    $form['intro'] = array(
+/**
+ * {@inheritdoc}
+ */
+public function buildForm(array $form, FormStateInterface $form_state) {
+  $form['intro'] = [
     '#markup' => '<div>' . t("This example uses a user autocomplete to dynamically change a node title autocomplete using #ajax.
       This is a way to get past the fact that we have no other way to provide context to the autocomplete function.
       It won't work very well unless you have a few users who have created some content that you can search for.") . '</div>',
-  );
+  ];
 
-  $form['author'] = array(
+  $form['author'] = [
     '#type' => 'textfield',
     '#title' => t('Choose the username that authored nodes you are interested in'),
-    // Since we just need simple user lookup, we can use the simplest function
-    // of them all, user_autocomplete().
+  // Since we just need simple user lookup, we can use the simplest function
+  // of them all, user_autocomplete().
     '#autocomplete_path' => 'user/autocomplete',
-    '#ajax' => array(
+    '#ajax' => [
       'callback' => '::ajax_example_node_by_author_ajax_callback',
       'wrapper' => 'autocomplete-by-node-ajax-replace',
-    ),
-  );
+    ],
+  ];
 
   // This form element with autocomplete will be replaced by #ajax whenever the
   // author changes, allowing the search to be limited by user.
-  $form['node'] = array(
+  $form['node'] = [
     '#type' => 'textfield',
     '#title' => t('Choose a node by title'),
     '#prefix' => '<div id="autocomplete-by-node-ajax-replace">',
     '#suffix' => '</div>',
     '#disabled' => TRUE,
-  );
+  ];
 
   // When the author changes in the author field, we'll change the
   // autocomplete_path to match.
@@ -60,26 +60,30 @@
     if (!empty($author)) {
       $autocomplete_path = 'examples/ajax_example/node_by_author_autocomplete/' . $author->uid;
       $form['node']['#autocomplete_path'] = $autocomplete_path;
-      $form['node']['#title'] = t('Choose a node title authored by %author', array('%author' => $author->name));
+      $form['node']['#title'] = t('Choose a node title authored by %author', ['%author' => $author->name]);
       $form['node']['#disabled'] = FALSE;
     }
   }
 
-  $form['actions'] = array(
+  $form['actions'] = [
     '#type' => 'actions',
-  );
+  ];
 
-  $form['actions']['submit'] = array(
+  $form['actions']['submit'] = [
     '#type' => 'submit',
     '#value' => t('Submit'),
-  );
+  ];
 
   return $form;
-  }
-  public function validateForm(array &$form, FormStateInterface $form_state) {
+}
+
+/**
+ * {@inheritdoc}
+ */
+public function validateForm(array &$form, FormStateInterface $form_state) {
   $title = $form_state['values']['node'];
   $author = $form_state['values']['author'];
-  $matches = array();
+  $matches = [];
 
   // We must have a valid user.
   $account = user_load_by_name($author);
@@ -99,46 +103,54 @@
     if (empty($node)) {
-      $form_state->setErrorByName($form['node'], t('Sorry, no node with nid %nid can be found', array('%nid' => $nid)));
+      $form_state->setErrorByName($form['node'], t('Sorry, no node with nid %nid can be found', ['%nid' => $nid]));
       return;
     }
     // BUT: Not everybody will have javascript turned on, or they might hit ESC
-  // and not use the autocomplete values offered. In that case, we can attempt
-  // to come up with a useful value. This is not absolutely necessary, and we
-  // *could* just emit a form_error() as below. Here we'll find the *first*
-  // matching title and assume that is adequate.
-  else {
-    $db = Database::getConnection();
-    $nid = $db->select('node')
-      ->fields('node', array('nid'))
-      ->condition('uid', $account->uid)
-      ->condition('title', $db->escapeLike($title) . '%', 'LIKE')
-      ->range(0, 1)
-      ->execute()
-      ->fetchField();
-  }
+    // and not use the autocomplete values offered. In that case, we can attempt
+    // to come up with a useful value. This is not absolutely necessary, and we
+    // *could* just emit a form_error() as below. Here we'll find the *first*
+    // matching title and assume that is adequate.
+    else {
+      $db = Database::getConnection();
+      $nid = $db->select('node')
+        ->fields('node', ['nid'])
+        ->condition('uid', $account->uid)
+        ->condition('title', $db->escapeLike($title) . '%', 'LIKE')
+        ->range(0, 1)
+        ->execute()
+        ->fetchField();
+    }
 
-  // Now, if we somehow found a nid, assign it to the node. If we failed, emit
-  // an error.
-  if (!empty($nid)) {
-    $form_state->setValue('node', $nid);
-  }
-  else {
-    $form_state->setErrorByName($form['node'], t('Sorry, no node starting with %title can be found', array('%title' => $title)));
-  }
+    // Now, if we somehow found a nid, assign it to the node. If we failed, emit
+    // an error.
+    if (!empty($nid)) {
+      $form_state->setValue('node', $nid);
+    }
+    else {
+      $form_state->setErrorByName($form['node'], t('Sorry, no node starting with %title can be found', ['%title' => $title]));
+    }
 
   }
 
+  /**
+   * AJAX callback for author form element.
+   */
   public function ajax_example_node_by_author_ajax_callback($form, $form_state) {
-  return $form['node'];
-}
+    return $form['node'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function submitForm(array &$form, FormStateInterface $form_state) {
     $node = Node::load($form_state->getValue('node'));
-  $account = User::load($node->uid);
-  drupal_set_message(t('You found node %nid with title !title_link, authored by !user_link',
-    array(
+    $account = User::load($node->uid);
+    drupal_set_message(t('You found node %nid with title !title_link, authored by !user_link',
+    [
       '%nid' => $node->nid,
       '!title_link' => l($node->title, 'node/' . $node->nid),
-      '!user_link' => theme('username', array('account' => $account)),
-    )
-  ));
+      '!user_link' => theme('username', ['account' => $account]),
+    ]
+    ));
   }
+
 }
diff -u b/ajax_example/src/Form/AjaxExampleAutotextfields.php b/ajax_example/src/Form/AjaxExampleAutotextfields.php
--- b/ajax_example/src/Form/AjaxExampleAutotextfields.php
+++ b/ajax_example/src/Form/AjaxExampleAutotextfields.php
@@ -6,7 +6,7 @@
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- *
+ * Show/hide textfields based on AJAX-enabled checkbox clicks.
  */
 class AjaxExampleAutotextfields extends FormBase {
 
@@ -78,8 +78,12 @@
   }
 
   /**
-   * Handles switching the available regions based on the selected theme.
-   */
+ * Callback for autotextfields.
+ *
+ * Selects the piece of the form we want to use as replacement text and returns
+ * it as a form (renderable array).
+ *
+ */
   public function prompt($form, FormStateInterface $form_state) {
     return $form['textfields'];
   }
diff -u b/ajax_example/src/Form/AjaxExampleDependentDropdown.php b/ajax_example/src/Form/AjaxExampleDependentDropdown.php
--- b/ajax_example/src/Form/AjaxExampleDependentDropdown.php
+++ b/ajax_example/src/Form/AjaxExampleDependentDropdown.php
@@ -6,7 +6,7 @@
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- *
+ * Repopulate a dropdown based on form state.
  */
 class AjaxExampleDependentDropdown extends FormBase {
 
@@ -18,7 +18,13 @@
   }
 
   /**
-   * {@inheritdoc}
+   * AJAX-based dropdown example form.
+   *
+   * A form with a dropdown whose options are dependent on a
+   * choice made in a previous dropdown.
+   *
+   * On changing the first dropdown, the options in the second
+   * are updated.
    */
   public function buildForm(array $form, FormStateInterface $form_state) {
     $options_first = _ajax_example_get_first_dropdown_options();
@@ -70,19 +76,19 @@
    * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
-    $trigger = (string)$form_state->getTriggeringElement()['#value'];
-  switch ($trigger) {
+    $trigger = (string) $form_state->getTriggeringElement()['#value'];
+    switch ($trigger) {
       case 'Submit':
-      // Submit: We're done.
-      drupal_set_message($this->t('Your values have been submitted. dropdown_first=@first, dropdown_second=@second', [
-        '@first' => $form_state->getValue('dropdown_first'),
-        '@second' => $form_state->getValue('dropdown_second'),
-      ]));
-      return;
-  }
-  // 'Choose' or anything else will cause rebuild of the form and present
-  // it again.
-  $form_state->setRebuild();
+        // Submit: We're done.
+        drupal_set_message($this->t('Your values have been submitted. dropdown_first=@first, dropdown_second=@second', [
+          '@first' => $form_state->getValue('dropdown_first'),
+          '@second' => $form_state->getValue('dropdown_second'),
+        ]));
+        return;
+    }
+    // 'Choose' or anything else will cause rebuild of the form and present
+    // it again.
+    $form_state->setRebuild();
   }
 
   /**
diff -u b/ajax_example/src/Form/AjaxExampleDependentDropdownDegardes.php b/ajax_example/src/Form/AjaxExampleDependentDropdownDegardes.php
--- b/ajax_example/src/Form/AjaxExampleDependentDropdownDegardes.php
+++ b/ajax_example/src/Form/AjaxExampleDependentDropdownDegardes.php
@@ -6,7 +6,24 @@
 use Drupal\Core\Form\FormStateInterface;
 
 /**
+ *Dropdown form based on previous choices.
  *
+ * A form with a dropdown whose options are dependent on a choice made in a
+ * previous dropdown.
+ *
+ * On changing the first dropdown, the options in the second
+ * are updated. Gracefully degrades if no javascript.
+ *
+ * A bit of CSS and javascript is required. The CSS hides the "add more" button
+ * if javascript is not enabled. The Javascript snippet is really only used
+ * to enable us to present the form in degraded mode without forcing the user
+ * to turn off Javascript.  Both of these are loaded by using the
+ * #attached FAPI property, so it is a good example of how to use that.
+ *
+ * The extra argument $no_js_use is here only to allow presentation of this
+ * form as if Javascript were not enabled. ajax_example_menu() provides two
+ * ways to call this form, one normal ($no_js_use = FALSE) and one simulating
+ * Javascript disabled ($no_js_use = TRUE).
  */
 class AjaxExampleDependentDropdownDegardes extends FormBase {
 
@@ -120,38 +137,15 @@
     // case t('OK'):
     // Submit: We're done.
     $trigger = $form_state->getTriggeringElement()['#value'];
-    switch($trigger){
-    case 'Choose':
-      $form_state->setRebuild();
-      break;
-    case 'OK':
-      drupal_set_message(t('Your values have been submitted. dropdown_first=@first, dropdown_second=@second', ['@first' => $form_state->getValue('dropdown_first'), '@second' => $form_state->getValue('dropdown_second')]));
-      break;
-
-
-      }
-
-
-
-
-    /*if ($form_state->getValue('continue_to_second') == 'Choose') {
-      // print_r("Why is this");.
-      $form_state->setRebuild();
-      if ($form_state->getValue('dropdown_second') == '') {
-        return;
-      }
-
+    switch ($trigger) {
+      case 'Choose':
+        $form_state->setRebuild();
+        break;
+
+      case 'OK':
+        drupal_set_message(t('Your values have been submitted. dropdown_first=@first, dropdown_second=@second', ['@first' => $form_state->getValue('dropdown_first'), '@second' => $form_state->getValue('dropdown_second')]));
+        break;
     }
-
-    if ($form_state->getValue('submit') == 'OK') {
-      drupal_set_message(t('Your values have been submitted. dropdown_first=@first, dropdown_second=@second', ['@first' => $form_state->getValue('dropdown_first'), '@second' => $form_state->getValue('dropdown_second')]));
-      return;
-    }*/
-    // default:
-    // drupal_set_message(t('Your values have been submitted. dropdown_first=@first, dropdown_second=@second', ['@first' => $form_state->getValue('dropdown_first'), '@second' => $form_state->getValue('dropdown_second')]));
-    // return;
-    // 'Choose' or anything else will cause rebuild of the form and present
-    // it again.
     $form_state->setRebuild();
   }
 
diff -u b/ajax_example/src/Form/AjaxExampleDynamicSectionsDegardes.php b/ajax_example/src/Form/AjaxExampleDynamicSectionsDegardes.php
--- b/ajax_example/src/Form/AjaxExampleDynamicSectionsDegardes.php
+++ b/ajax_example/src/Form/AjaxExampleDynamicSectionsDegardes.php
@@ -8,7 +8,17 @@
 use Drupal\Core\Url;
 
 /**
+ * Dynamically-enabled form with graceful no-JS degradation.
  *
+ * Example of a form with portions dynamically enabled or disabled, but
+ * with graceful degradation in the case of no javascript.
+ *
+ * The idea here is that certain parts of the form don't need to be displayed
+ * unless a given option is selected, but then they should be displayed and
+ * configured.
+ *
+ * The third $no_js_use argument is strictly for demonstrating operation
+ * without javascript, without making the user/developer turn off javascript.
  */
 class AjaxExampleDynamicSectionsDegardes extends FormBase {
 
@@ -20,7 +30,7 @@
   }
 
   /**
-   * {@inheritdoc}
+   *
    */
   public function buildForm(array $form, FormStateInterface $form_state, $no_js_use = FALSE) {
     $url = Url::fromUri('internal:/examples/ajax-example/dynamic-sections-no_js');
@@ -29,7 +39,9 @@
     // Prepare link for multiple arguments.
     $urltwo = Url::fromUri('internal:/examples/ajax-example/dynamic-sections');
     $linktwo = Link::fromTextAndUrl($this->t('examples/ajax-example/dynamic-sections'), $urltwo)->toString();
-
+    // Attach the CSS and JS we need to show this with and without javascript.
+    // Without javascript we need an extra "Choose" button, and this is
+    // hidden when we have javascript enabled.
     $form['#attached']['library'][] = 'ajax_example/ajax_eample.dropdown';
 
     $form['description'] = [
@@ -99,11 +111,11 @@
             '#type' => 'radios',
             '#title' => t('Who was the first president of the United States'),
             '#options' => [
-            'George Bush' => 'George Bush',
-            'Adam McGuire' => 'Adam McGuire',
-            'Abraham Lincoln' =>'Abraham Lincoln',
-            'George Washington' =>'George Washington',
-          ],
+              'George Bush' => 'George Bush',
+              'Adam McGuire' => 'Adam McGuire',
+              'Abraham Lincoln' => 'Abraham Lincoln',
+              'George Washington' => 'George Washington',
+            ],
 
           ];
           break;
@@ -113,8 +125,8 @@
             '#type' => 'radios',
             '#title' => $this->t('Was George Washington the first president of the United States?'),
             '#options' => [
-            'George Washington' => 'True',
-            0 => 'False',
+              'George Washington' => 'True',
+              0 => 'False',
             ],
             '#description' => $this->t('Click "True" if you think George Washington was the first president of the United States.'),
           ];
@@ -138,42 +150,40 @@
   }
 
   /**
-   * Submit function for ajax_example_dynamic_sections().
+   * Final submit handler.
+   *
+   * Reports what values were finally set.
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
-    // This is only executed when a button is pressed, not when the AJAXified
+    // This is only executed when a button is pressed, not when the AJAXfield
     // select is changed.
     // Now handle the case of the next, previous, and submit buttons.
     // Only submit will result in actual submission, all others rebuild.
-    if($form_state->getValue('question_type_submit') == 'Choose'){
-          //print_r("Why is this");
-          $form_state->setValue('question_type_select', $form_state->getUserInput()['question_type_select']);
-          $form_state->setRebuild();
-}
-
-    if($form_state->getValue('submit') == 'Submit your answer'){
-        $form_state->setRebuild(FALSE);
-
-        $answer = $form_state->getValue('question');
-        print_r($answers);
-        // Special handling for the checkbox.
-        if ($answer == 1 && $form['questions_fieldset']['question']['#type'] == 'checkbox') {
-          $answer = $form['questions_fieldset']['question']['#title'];
-        }
-        if ($answer == $this->t('George Washington')) {
-          drupal_set_message($this->t('You got the right answer: @answer', ['@answer' => $answer]));
-        }
-        else {
-          drupal_set_message($this->t('Sorry, your answer (@answer) is wrong', ['@answer' => $answer]));
-        }
-        return;
+    if ($form_state->getValue('question_type_submit') == 'Choose') {
+      $form_state->setValue('question_type_select', $form_state->getUserInput()['question_type_select']);
+      $form_state->setRebuild();
+    }
 
+    if ($form_state->getValue('submit') == 'Submit your answer') {
+      $form_state->setRebuild(FALSE);
+      $answer = $form_state->getValue('question');
+      print_r($answers);
+      // Special handling for the checkbox.
+      if ($answer == 1 && $form['questions_fieldset']['question']['#type'] == 'checkbox') {
+        $answer = $form['questions_fieldset']['question']['#title'];
       }
-
+      if ($answer == $this->t('George Washington')) {
+        drupal_set_message($this->t('You got the right answer: @answer', ['@answer' => $answer]));
+      }
+      else {
+        drupal_set_message($this->t('Sorry, your answer (@answer) is wrong', ['@answer' => $answer]));
+      }
+      return;
+    }
+    // Sets the form to be rebuilt after processing.
     $form_state->setRebuild();
   }
 
-
   /**
    * Callback for the select element.
    *
diff -u b/ajax_example/src/Form/AjaxExampleNodeFormAlter.php b/ajax_example/src/Form/AjaxExampleNodeFormAlter.php
--- b/ajax_example/src/Form/AjaxExampleNodeFormAlter.php
+++ b/ajax_example/src/Form/AjaxExampleNodeFormAlter.php
@@ -4,15 +4,22 @@
 
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\Core\Database\Database;
-use Drupal\Core\Database\Query\Condition;
-use Drupal\node\Entity\Node;
+use Drupal\Core\Database\Connection;
 
 /**
  *
  */
 class AjaxExampleNodeFormAlter extends FormBase {
 
+  protected $connection;
+
+  /**
+   *
+   */
+  public function __construct(Connection $connection) {
+    $this->connection = $connection;
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -27,119 +34,129 @@
     $node = $form['#node'];
-  $form['ajax_example_1'] = array(
-    '#type' => 'checkbox',
-    '#title' => t('AJAX Example 1'),
-    '#description' => t('Enable to show second field.'),
-    '#default_value' => $node->ajax_example['example_1'],
-    '#ajax' => array(
-      'callback' => '::ajax_example_form_node_callback',
-      'wrapper' => 'ajax-example-form-node',
-      'effect' => 'fade',
-    ),
-  );
-  $form['container'] = array(
-    '#prefix' => '<div id="ajax-example-form-node">',
-    '#suffix' => '</div>',
-  );
-
-  // If the state values exist and 'ajax_example_1' state value is 1 or
-  // if the state values don't exist and 'example1' variable is 1 then
-  // display the ajax_example_2 field.
-  if (!empty($form_state->getValue('ajax_example_1')) && $form_state->getValue('ajax_example_1') == 1
+    $form['ajax_example_1'] = [
+      '#type' => 'checkbox',
+      '#title' => t('AJAX Example 1'),
+      '#description' => t('Enable to show second field.'),
+      '#default_value' => $node->ajax_example['example_1'],
+      '#ajax' => [
+        'callback' => '::ajax_example_form_node_callback',
+        'wrapper' => 'ajax-example-form-node',
+        'effect' => 'fade',
+      ],
+    ];
+    $form['container'] = [
+      '#prefix' => '<div id="ajax-example-form-node">',
+      '#suffix' => '</div>',
+    ];
+
+    // If the state values exist and 'ajax_example_1' state value is 1 or
+    // if the state values don't exist and 'example1' variable is 1 then
+    // display the ajax_example_2 field.
+    if (!empty($form_state->getValue('ajax_example_1')) && $form_state->getValue('ajax_example_1') == 1
       || empty($form_state->getValue()) && $node->ajax_example['example_1']) {
 
-    $form['container']['ajax_example_2'] = array(
-      '#type' => 'textfield',
-      '#title' => t('AJAX Example 2'),
-      '#description' => t('AJAX Example 2'),
-      '#default_value' => empty($form_state->getValue('ajax_example_2')) ? $node->ajax_example['example_2'] : $form_state->getValue('ajax_example_2'),
-    );
+      $form['container']['ajax_example_2'] = [
+        '#type' => 'textfield',
+        '#title' => t('AJAX Example 2'),
+        '#description' => t('AJAX Example 2'),
+        '#default_value' => empty($form_state->getValue('ajax_example_2')) ? $node->ajax_example['example_2'] : $form_state->getValue('ajax_example_2'),
+      ];
+    }
   }
-}
-  //callback of ajax
-  function ajax_example_form_node_callback($form, $form_state) {
-  return $form['container'];
-}
-   /**
+
+  /**
+   * Callback of ajax.
+   */
+  public function ajax_example_form_node_callback($form, $form_state) {
+    return $form['container'];
+  }
+
+  /**
    *
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
     $values = $form_state->getValue();
-  // Move the new data into the node object.
-  $node->ajax_example['example_1'] = $values['ajax_example_1'];
-  // Depending on the state of ajax_example_1; it may not exist.
-  $node->ajax_example['example_2'] = isset($values['ajax_example_2']) ? $values['ajax_example_2'] : '';
+    // Move the new data into the node object.
+    $node->ajax_example['example_1'] = $values['ajax_example_1'];
+    // Depending on the state of ajax_example_1; it may not exist.
+    $node->ajax_example['example_2'] = isset($values['ajax_example_2']) ? $values['ajax_example_2'] : '';
   }
 
+  /**
+   *
+   */
   public function ajax_example_node_prepare($node) {
-  if (empty($node->ajax_example)) {
-    // Set default values, since this only runs when adding a new node.
-    $node->ajax_example['example_1'] = 0;
-    $node->ajax_example['example_2'] = '';
+    if (empty($node->ajax_example)) {
+      // Set default values, since this only runs when adding a new node.
+      $node->ajax_example['example_1'] = 0;
+      $node->ajax_example['example_2'] = '';
+    }
   }
-}
 
-/**
- * Implements hook_node_load().
- *
- * @see ajax_example_form_node_form_alter()
- */
-public function ajax_example_node_load($nodes, $types) {
-  $result = db_query('SELECT * FROM {ajax_example_node_form_alter} WHERE nid IN(:nids)', array(':nids' => array_keys($nodes)))->fetchAllAssoc('nid');
+  /**
+   * Implements hook_node_load().
+   *
+   * @see ajax_example_form_node_form_alter()
+   */
+  public function ajax_example_node_load($nodes, $types) {
+    $result = $this->connection->query('SELECT * FROM {ajax_example_node_form_alter} WHERE nid IN(:nids)', [':nids' => array_keys($nodes)])->fetchAllAssoc('nid');
 
-  foreach ($nodes as &$node) {
-    $node->ajax_example['example_1']
+    foreach ($nodes as &$node) {
+      $node->ajax_example['example_1']
       = isset($result[$node->nid]->example_1) ?
       $result[$node->nid]->example_1 : 0;
-    $node->ajax_example['example_2']
+      $node->ajax_example['example_2']
       = isset($result[$node->nid]->example_2) ?
       $result[$node->nid]->example_2 : '';
+    }
   }
-}
 
-/**
- * Implements hook_node_insert().
- *
- * @see ajax_example_form_node_form_alter()
- */
-public function ajax_example_node_insert($node) {
-  if (isset($node->ajax_example)) {
-    db_insert('ajax_example_node_form_alter')
-      ->fields(array(
-        'nid' => $node->nid,
-        'example_1' => $node->ajax_example['example_1'],
-        'example_2' => $node->ajax_example['example_2'],
-      ))
-      ->execute();
+  /**
+   * Implements hook_node_insert().
+   *
+   * @see ajax_example_form_node_form_alter()
+   */
+  public function ajax_example_node_insert($node) {
+    if (isset($node->ajax_example)) {
+      $this->connection->insert('ajax_example_node_form_alter')
+        ->fields([
+          'nid' => $node->nid,
+          'example_1' => $node->ajax_example['example_1'],
+          'example_2' => $node->ajax_example['example_2'],
+        ])
+        ->execute();
+    }
   }
-}
 
-/**
- * Implements hook_node_update().
- * @see ajax_example_form_node_form_alter()
- */
-public function ajax_example_node_update($node) {
-  if (db_select('ajax_example_node_form_alter', 'a')->fields('a')->condition('nid', $node->nid, '=')->execute()->fetchAssoc()) {
-    db_update('ajax_example_node_form_alter')
-      ->fields(array(
-        'example_1' => $node->ajax_example['example_1'],
-        'example_2' => $node->ajax_example['example_2'],
-      ))
+  /**
+   * Implements hook_node_update().
+   *
+   * @see ajax_example_form_node_form_alter()
+   */
+  public function ajax_example_node_update($node) {
+    if ($this->connection->select('ajax_example_node_form_alter', 'a')->fields('a')->condition('nid', $node->nid, '=')->execute()->fetchAssoc()) {
+      $this->connection->update('ajax_example_node_form_alter')
+        ->fields([
+          'example_1' => $node->ajax_example['example_1'],
+          'example_2' => $node->ajax_example['example_2'],
+        ])
+        ->condition('nid', $node->nid)
+        ->execute();
+    }
+    else {
+      // Cleaner than doing it again.
+      ajax_example_node_insert($node);
+    }
+  }
+
+  /**
+   * Implements hook_node_delete().
+   *
+   * @see ajax_example_form_node_form_alter()
+   */
+  public function ajax_example_node_delete($node) {
+    $this->connection->delete('ajax_example_node_form_alter')
       ->condition('nid', $node->nid)
       ->execute();
   }
-  else {
-    // Cleaner than doing it again.
-    ajax_example_node_insert($node);
-  }
-}
 
-/**
- * Implements hook_node_delete().
- * @see ajax_example_form_node_form_alter()
- */
-public function ajax_example_node_delete($node) {
-  db_delete('ajax_example_node_form_alter')
-    ->condition('nid', $node->nid)
-    ->execute();
-}
 }
diff -u b/ajax_example/src/Form/AjaxExampleProgressBar.php b/ajax_example/src/Form/AjaxExampleProgressBar.php
--- b/ajax_example/src/Form/AjaxExampleProgressBar.php
+++ b/ajax_example/src/Form/AjaxExampleProgressBar.php
@@ -8,7 +8,7 @@
 use Drupal\Core\Url;
 
 /**
- *
+ *Progress bar example.
  */
 class AjaxExampleProgressBar extends FormBase {
 
@@ -20,7 +20,7 @@
   }
 
   /**
-   * {@inheritdoc}
+   * Build a landing-page form for the progress bar example.
    */
   public function buildForm(array $form, FormStateInterface $form_state) {
     $form['time'] = \Drupal::time()->getRequestTime();
diff -u b/ajax_example/src/Form/AjaxExampleSubmitDriven.php b/ajax_example/src/Form/AjaxExampleSubmitDriven.php
--- b/ajax_example/src/Form/AjaxExampleSubmitDriven.php
+++ b/ajax_example/src/Form/AjaxExampleSubmitDriven.php
@@ -6,7 +6,7 @@
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- *
+ * Submit a form without a page reload.
  */
 class AjaxExampleSubmitDriven extends FormBase {
 
diff -u b/ajax_example/src/Form/AjaxExampleUniquecomplete.php b/ajax_example/src/Form/AjaxExampleUniquecomplete.php
--- b/ajax_example/src/Form/AjaxExampleUniquecomplete.php
+++ b/ajax_example/src/Form/AjaxExampleUniquecomplete.php
@@ -9,7 +9,11 @@
 use Drupal\node\Entity\Node;
 
 /**
+ *An autocomplete form to look up nodes by title.
  *
+ * An autocomplete form which looks up nodes by title in the node table,
+ * but must keep track of the nid, because titles are certainly not guaranteed
+ * to be unique.
  */
 class AjaxExampleUniquecomplete extends FormBase {
 
@@ -48,7 +52,7 @@
   }
 
   /**
-   *
+   * {@inheritdoc}
    */
   public function validateForm(array &$form, FormStateInterface $form_state) {
     $title = $form_state->getValue('node');
@@ -94,7 +98,7 @@
   }
 
   /**
-   *
+   * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
     $node = Node::load($form_state->getValue(['values', 'node']));
diff -u b/ajax_example/src/Form/AjaxExampleWizard.php b/ajax_example/src/Form/AjaxExampleWizard.php
--- b/ajax_example/src/Form/AjaxExampleWizard.php
+++ b/ajax_example/src/Form/AjaxExampleWizard.php
@@ -2,13 +2,11 @@
 
 namespace Drupal\ajax_example\Form;
 
-use Drupal\Component\Utility\Html;
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Url;
 use Drupal\Core\Link;
 use Drupal\Core\Ajax\AjaxResponse;
-use Drupal\Core\Ajax\ReplaceCommand;
 use Drupal\Core\Ajax\HtmlCommand;
 
 /**
@@ -36,8 +34,8 @@
     $linktwo = Link::fromTextAndUrl($this->t('examples/ajax-example/wizard'), $urltwo)
       ->toString();
 
-//    $form['#prefix'] = '<div id="wizard-form-wrapper">';
-//    $form['#suffix'] = '</div>';
+    // $form['#prefix'] = '<div id="wizard-form-wrapper">';
+    //    $form['#suffix'] = '</div>';
     // We want to deal with hierarchical form values.
     $form['#tree'] = TRUE;
     $form['description'] = [
@@ -78,7 +76,6 @@
       ];
     }
 
-
     // This simply allows us to demonstrate no-javascript use without
     // actually turning off javascript in the browser. Removing the #ajax
     // element turns off AJAX behaviors on that element and as a result
only in patch2:
unchanged:
--- /dev/null
+++ b/ajax_example/src/Form/AjaxExampleWizard_mine_with_error.php
@@ -0,0 +1,203 @@
+<?php
+
+namespace Drupal\ajax_example\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Url;
+use Drupal\Core\Link;
+
+/**
+ *
+ */
+class AjaxExampleWizard extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormID() {
+    return 'ajax_example_wizard';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state, $no_js_use = FALSE) {
+    $url = Url::fromUri('internal:/examples/ajax-example/wizard-nojs');
+    $link = Link::fromTextAndUrl($this->t('examples/ajax-example/wizard-nojs'), $url)->toString();
+
+    // Prepare link for multiple arguments.
+    $urltwo = Url::fromUri('internal:/examples/ajax-example/wizard');
+    $linktwo = Link::fromTextAndUrl($this->t('examples/ajax-example/wizard'), $urltwo)->toString();
+
+    $form['#prefix'] = '<div id="wizard-form-wrapper">';
+    $form['#suffix'] = '</div>';
+    // We want to deal with hierarchical form values.
+    $form['#tree'] = TRUE;
+    $form['description'] = [
+      '#markup' =>t('This example is a step-by-step wizard. The @link does it without page reloads; the @link1 is the same code but simulates a non-javascript environment, showing it with page reloads.', ['@link' => $linktwo, '@link1' => $link]),
+    ];
+
+    // $form_state['storage'] has no specific drupal meaning, but it is
+    // traditional to keep variables for multistep forms there.
+    //$step['step'] = !empty($form_state->getStorage()) ? $form_state->getStorage() : 1 ;
+
+    //$form_state->setStorage($step);
+    $form['step'] = [
+      '#type' => 'hidden',
+      '#value' => !empty($form_state->getValue('step')) ? $form_state->getValue('step') : 1,
+    ];
+    if(empty($form_state->getValue('step')))
+      $form_state->setValue('step', 1);
+    $step_name = $form_state->getValue('step');
+    switch ($step_name) {
+      case 1:
+        $form['step1'] = [
+          '#type' => 'fieldset',
+          '#title' => t('Step 1: Personal details'),
+        ];
+        $form['step1']['name'] = [
+          '#type' => 'textfield',
+          '#title' => t('Your name'),
+          '#default_value' => empty($form_state->getValue(['step1', 'name']) ? '' : $form_state->getValue(['step1', 'name'])),
+          '#required' => TRUE,
+        ];
+        break;
+
+      case 2:
+        $form['step2'] = [
+          '#type' => 'fieldset',
+          '#title' => t('Step 2: Street address info'),
+        ];
+        $form['step2']['address'] = [
+          '#type' => 'textfield',
+          '#title' => t('Your street address'),
+          '#default_value' => empty($form_state->getValue(['step1', 'address']) ? '' : $form_state->getValue(['step1', 'address'])),
+          '#required' => TRUE,
+        ];
+        break;
+
+      case 3:
+        $form['step3'] = [
+          '#type' => 'fieldset',
+          '#title' => t('Step 3: City info'),
+        ];
+        $form['step3']['city'] = [
+          '#type' => 'textfield',
+          '#title' => t('Your city'),
+          '#default_value' => empty($form_state->getValue(['step1', 'city']) ? '' : $form_state->getValue(['step1', 'city'])),
+          '#required' => TRUE,
+        ];
+        break;
+    }
+    if ($step_name == 3) {
+      $form['submit'] = [
+        '#type' => 'submit',
+        '#value' => t("Submit your information"),
+      ];
+    }
+    if ($step_name < 3) {
+      $form['next'] = [
+        '#type' => 'submit',
+        '#value' => t('Next step'),
+        '#ajax' => [
+          'wrapper' => 'wizard-form-wrapper',
+          'callback' => '::functionajax',
+        ],
+      ];
+    }
+    if ($step_name > 1) {
+      $form['prev'] = [
+        '#type' => 'submit',
+        '#value' => t("Previous step"),
+
+      // Since all info will be discarded, don't validate on 'prev'.
+        '#limit_validation_errors' => [],
+      // #submit is required to use #limit_validation_errors.
+        '#submit' => ['::submitForm'],
+        '#ajax' => [
+          'wrapper' => 'wizard-form-wrapper',
+          'callback' => '::fuctionajax',
+        ],
+      ];
+    }
+
+    // This simply allows us to demonstrate no-javascript use without
+    // actually turning off javascript in the browser. Removing the #ajax
+    // element turns off AJAX behaviors on that element and as a result
+    // ajax.js doesn't get loaded.
+    // For demonstration only! You don't need this.
+    if ($no_js_use) {
+      // Remove the #ajax from the above, so ajax.js won't be loaded.
+      // For demonstration only.
+      unset($form['next']['#ajax']);
+      unset($form['prev']['#ajax']);
+    }
+
+    return $form;
+  }
+
+  /**
+   * Wizard callback function.
+   *
+   * @param array $form
+   *   Form API form.
+   * @param array $form_state
+   *   Form API form.
+   *
+   * @return array
+   *   Form array.
+   */
+  public function functionajax($form, $form_state) {
+    if ($form_state->getTriggeringElement()['#value'] == $this->t('Next step')) {
+        $inc = $form_state->getValue('step');
+        $inc++;
+        $form_state->setValue('step', $inc);
+      }
+      elseif ($form_state->getTriggeringElement()['#value']->__toString() == $this->t('Previous step')) {
+        $dec = $form_state->getValue('step');
+        $dec--;
+        $form_state->setValue('step', $dec);
+      }
+    return $form;
+  }
+
+  /**
+   * Submit function for ajax_example_wizard.
+   *
+   * In AJAX this is only submitted when the final submit button is clicked,
+   * but in the non-javascript situation, it is submitted with every
+   * button click.
+   */
+
+
+    // Save away the current information.
+
+public function submitForm(array &$form, FormStateInterface $form_state) {
+      /*if ($form_state->getTriggeringElement()['#value'] == $this->t('Next step')) {
+        $inc = $form_state->getValue('step');
+        $inc++;
+        $form_state->setValue('step', $inc);
+      }
+      elseif ($form_state->getTriggeringElement()['#value']->__toString() == $this->t('Previous step')) {
+        $dec = $form_state->getValue('step');
+        $dec--;
+        $form_state->setValue('step', $dec);
+      }*/
+      if ($form_state->getTriggeringElement()['#value'] == $this->t('Submit your information')) {
+      $value_message = $this->t('Your information has been submitted:') . ' ';
+      foreach ($form_state->getValue('value') as $step => $values) {
+        $value_message .= "$step: ";
+        foreach ($values as $key => $value) {
+          $value_message .= "$key=$value, ";
+        }
+      }
+      drupal_set_message($value_message);
+      $form_state->setRebuild(FALSE);
+      // Redirect to #action, else return.
+      return;
+    }
+
+  }
+
+}