Randomg things.

web/modules/custom/dc_tests/dc_tests.libraries.yml

@@ -0,0 +1,5 @@
+testing:
+  js:
+    js/testing.js: {}
+  dependencies:
+    - core/drupal

web/modules/custom/dc_tests/dc_tests.module

@@ -0,0 +1,5 @@
+<?php
+
+function dc_tests_preprocess_node(&$variables) {
+  $variables['#attached']['library'][] = 'dc_tests/testing';
+}

web/modules/custom/dc_tests/js/testing.js

@@ -0,0 +1,10 @@
+((Drupal, once) => {
+  Drupal.behaviors.myBehavior = {
+    attach(context) {
+      let target = once('myBehavior', 'body');
+      target.forEach((t) => {
+        alert('Behavior attached test');
+      });
+    },
+  };
+})(Drupal, once);

web/modules/custom/ufc/templates/ufc-recent-fights.html.twig

@@ -0,0 +1 @@
+<h1>Hello World</h1>