diff --git a/core/lib/Drupal/Core/Ajax/MessageCommand.php b/core/lib/Drupal/Core/Ajax/MessageCommand.php
index 4709257bb1..653041c39b 100644
--- a/core/lib/Drupal/Core/Ajax/MessageCommand.php
+++ b/core/lib/Drupal/Core/Ajax/MessageCommand.php
@@ -30,34 +30,34 @@ class MessageCommand implements CommandInterface, CommandWithAttachedAssetsInter
    *
    * @var string
    */
-  protected $messageWrapperQuerySelector;
+  protected $wrapperQuerySelector;
 
   /**
    * The options passed to Drupal.message().add().
    *
    * @var array
    */
-  protected $messageOptions;
+  protected $options;
 
   /**
    * Constructs a MessageCommand object.
    *
    * @param string $message
    *   The text of the message.
-   * @param string|null $messageWrapperQuerySelector
+   * @param string|null $wrapper_query_selector
    *   The query selector of the element to display messages in when they
    *   should be displayed somewhere other than the default.
    *   @see Drupal.Message.defaultWrapper()
-   * @param array $messageOptions
+   * @param array $options
    *   The options passed to Drupal.message().add().
-   * @param bool $clearPrevious
-   *   Whether to clear previous messages.
+   * @param bool $clear_previous
+   *   If TRUE, previous messages will be cleared first.
    */
-  public function __construct($message, $messageWrapperQuerySelector = NULL, array $messageOptions = [], $clearPrevious = TRUE) {
+  public function __construct($message, $wrapper_query_selector = NULL, array $options = [], $clear_previous = TRUE) {
     $this->message = $message;
-    $this->messageWrapperQuerySelector = $messageWrapperQuerySelector;
-    $this->messageOptions = $messageOptions;
-    $this->clearPrevious = $clearPrevious;
+    $this->wrapperQuerySelector = $wrapper_query_selector;
+    $this->options = $options;
+    $this->clearPrevious = $clear_previous;
   }
 
   /**
@@ -67,8 +67,8 @@ public function render() {
     return [
       'command' => 'message',
       'message' => $this->message,
-      'messageWrapperQuerySelector' => $this->messageWrapperQuerySelector,
-      'messageOptions' => $this->messageOptions,
+      'messageWrapperQuerySelector' => $this->wrapperQuerySelector,
+      'messageOptions' => $this->options,
       'clearPrevious' => $this->clearPrevious,
     ];
   }
diff --git a/core/misc/ajax.es6.js b/core/misc/ajax.es6.js
index cd70804c98..905559c921 100644
--- a/core/misc/ajax.es6.js
+++ b/core/misc/ajax.es6.js
@@ -1564,20 +1564,20 @@
     },
 
     /**
-     * Command to use Drupal.Message() via AJAX command.
+     * Command to add a message to the message area.
      *
      * @param {Drupal.Ajax} [ajax]
      *   {@link Drupal.Ajax} object created by {@link Drupal.ajax}.
      * @param {object} response
      *   The response from the Ajax request.
      * @param {string} response.messageWrapperQuerySelector
-     *   The zone where to add the message. If null a default will be used.
+     *   The zone where to add the message. If null, the default will be used.
      * @param {string} response.message
      *   The message text.
      * @param {string} response.messageOptions
      *   The options argument for Drupal.Message().add().
      * @param {bool} response.clearPrevious
-     *   If TRUE, clear previous messages.
+     *   If true, clear previous messages.
      */
     message(ajax, response) {
       const messages = new Drupal.Message(
diff --git a/core/tests/Drupal/FunctionalJavascriptTests/Ajax/MessageTest.php b/core/tests/Drupal/FunctionalJavascriptTests/Ajax/MessageTest.php
index 65b6c01384..872d42ed32 100644
--- a/core/tests/Drupal/FunctionalJavascriptTests/Ajax/MessageTest.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/Ajax/MessageTest.php
@@ -63,7 +63,6 @@ public function testMessageCommand() {
       });
       $this->assertTrue($expected_count);
     }
-
   }
 
   /**