diff --git a/core/lib/Drupal/Core/Render/Element/Splitbutton.php b/core/lib/Drupal/Core/Render/Element/Splitbutton.php
index 7d927aa960..f3e350c1ec 100644
--- a/core/lib/Drupal/Core/Render/Element/Splitbutton.php
+++ b/core/lib/Drupal/Core/Render/Element/Splitbutton.php
@@ -40,6 +40,29 @@
  * - #dropbutton_type: The value is copied or appended to #splitbutton_type.
  *   This will be removed in Drupal 10.
  *
+ * Usage Example:
+ * @code
+ * $form['actions']['splitbutton_actions'] = [
+ *   '#type' => 'splitbutton',
+ *   '#splitbutton_type' => 'small',
+ *   '#splitbutton_items' => [
+ *     'added_link' => [
+ *       '#type' => 'link',
+ *       '#title' => $this->t('Simple Form'),
+ *       '#url' => Url::fromRoute('route.for.thelink'),
+ *     ],
+ *     'added_button' => [
+ *       '#type' => 'button',
+ *       '#value' => $this->t('Added Button'),
+ *     ],
+ *     'another_added_button' => [
+ *       '#type' => 'submit',
+ *       '#value' => $this->t('Another Added Button'),
+ *     ],
+ *   ],
+ * ];
+ * @endcode
+ *
  * @RenderElement("splitbutton")
  */
 class Splitbutton extends FormElement {
diff --git a/core/misc/splitbutton/splitbutton-init.es6.js b/core/misc/splitbutton/splitbutton-init.es6.js
index 6304738f1a..bbf4a6756c 100644
--- a/core/misc/splitbutton/splitbutton-init.es6.js
+++ b/core/misc/splitbutton/splitbutton-init.es6.js
@@ -17,11 +17,9 @@
       const $splitbuttons = $(context)
         .find('[data-drupal-splitbutton-multiple]')
         .once('splitbutton');
-      if ($splitbuttons.length) {
-        for (let i = 0; i < $splitbuttons.length; i++) {
-          Drupal.splitbuttons.push(new Drupal.SplitButton($splitbuttons[i]));
-        }
-      }
+      $splitbuttons.map((index, splitbutton) =>
+        Drupal.splitbuttons.push(new Drupal.SplitButton(splitbutton)),
+      );
     },
   };
 
diff --git a/core/misc/splitbutton/splitbutton-init.js b/core/misc/splitbutton/splitbutton-init.js
index b09c1963f1..d7f6cfcd84 100644
--- a/core/misc/splitbutton/splitbutton-init.js
+++ b/core/misc/splitbutton/splitbutton-init.js
@@ -9,12 +9,9 @@
   Drupal.behaviors.SplitButton = {
     attach: function attach(context) {
       var $splitbuttons = $(context).find('[data-drupal-splitbutton-multiple]').once('splitbutton');
-
-      if ($splitbuttons.length) {
-        for (var i = 0; i < $splitbuttons.length; i++) {
-          Drupal.splitbuttons.push(new Drupal.SplitButton($splitbuttons[i]));
-        }
-      }
+      $splitbuttons.map(function (index, splitbutton) {
+        return Drupal.splitbuttons.push(new Drupal.SplitButton(splitbutton));
+      });
     }
   };
   Drupal.splitbuttons = [];
diff --git a/core/tests/Drupal/KernelTests/Component/Render/SplitbuttonDeprecationTest.php b/core/tests/Drupal/KernelTests/Component/Render/SplitbuttonDeprecationTest.php
new file mode 100644
index 0000000000..64de2aaf7f
--- /dev/null
+++ b/core/tests/Drupal/KernelTests/Component/Render/SplitbuttonDeprecationTest.php
@@ -0,0 +1,69 @@
+<?php
+
+namespace Drupal\KernelTests\Component\Render;
+
+use Drupal\Core\Url;
+use Drupal\Core\Render\Element\Splitbutton;
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * Provides a test that checks for deprecated splitbutton properties.
+ *
+ * @group Render
+ * @group legacy
+ */
+class SplitbuttonDeprecationTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['splitbutton_test'];
+
+  /**
+   * Check for deprecated splitbutton properties.
+   *
+   * @expectedDeprecation The #dropbutton_type property in splitbutton is deprecated in drupal:9.1.0 and is removed from drupal:10.0.0.
+   * @expectedDeprecation The #links property in splitbutton is deprecated in drupal:9.1.0 and is removed from drupal:10.0.0.
+   */
+  public function testDeprecation() {
+    $element_with_deprecated_properties = [
+      '#type' => 'splitbutton',
+      '#dropbutton_type' => 'small',
+      '#links' => [
+        'one' => [
+          'title' => 'one',
+          'url' => Url::fromRoute('splitbutton.test_link_1'),
+        ],
+        'two' => [
+          'title' => 'two',
+          'url' => Url::fromRoute('splitbutton.test_link_2'),
+        ],
+      ],
+    ];
+
+    $plugin_definition = [
+      'id' => 'splitbutton',
+      'class' => 'Drupal\Core\Render\Element\Splitbutton',
+      'provider' => 'core',
+    ];
+
+    $splitbutton_element = new Splitbutton([], 'splitbutton', $plugin_definition);
+    $splitbutton = $splitbutton_element::preRenderSplitbutton($element_with_deprecated_properties);
+
+    $expected_array_keys = [
+      '#type',
+      '#dropbutton_type',
+      '#links',
+      '#variants',
+      '#trigger_id',
+      '#toggle_attributes',
+      '#main_element',
+      '#splitbutton_item_list',
+      '#splitbutton_multiple',
+      '#attributes',
+    ];
+
+    $this->assertEquals($expected_array_keys, array_keys($splitbutton));
+  }
+
+}