Issue #3519888 by jurgenhaas: ECA Misc: Add condition to see if the current request is ajax

Closes #3519888

modules/miscellaneous/src/Plugin/ECA/Condition/IsAjax.php

+<?php
+
+namespace Drupal\eca_misc\Plugin\ECA\Condition;
+
+use Drupal\Core\Ajax\AjaxHelperTrait;
+use Drupal\eca\Plugin\ECA\Condition\ConditionBase;
+
+/**
+ * Condition plugin to determine if the current request is an AJAX request.
+ *
+ * @EcaCondition(
+ *   id = "eca_is_ajax",
+ *   label = "Is Ajax",
+ *   description = @Translation("Determines if the current request is an AJAX request."),
+ *   eca_version_introduced = "2.1.8"
+ * )
+ */
+class IsAjax extends ConditionBase {
+
+  use AjaxHelperTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function evaluate(): bool {
+    $result = $this->isAjax();
+    return $this->negationCheck($result);
+  }
+
+}