first commit

media/com_fields/js/admin-field-edit.js

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+/**
+ * @copyright  (C) 2018 Open Source Matters, Inc. <https://www.joomla.org>
+ * @license    GNU General Public License version 2 or later; see LICENSE.txt
+ */
+
+document.addEventListener('DOMContentLoaded', () => {
+
+  const title = document.getElementById('jform_title');
+  title.dpOldValue = title.value;
+  title.addEventListener('change', ({
+    currentTarget
+  }) => {
+    const label = document.getElementById('jform_label');
+    const changedTitle = currentTarget;
+    if (changedTitle.dpOldValue === label.value) {
+      label.value = changedTitle.value;
+    }
+    changedTitle.dpOldValue = changedTitle.value;
+  });
+});