diff --cc core/modules/file/file.module
index ee12a41,0ee7528..0000000
--- a/core/modules/file/file.module
+++ b/core/modules/file/file.module
diff --git a/core/modules/file/templates/file-managed-file.html.twig b/core/modules/file/templates/file-managed-file.html.twig
index 7a87511..fdd2b3c 100644
--- a/core/modules/file/templates/file-managed-file.html.twig
+++ b/core/modules/file/templates/file-managed-file.html.twig
@@ -12,6 +12,11 @@
  * @ingroup themeable
  */
 #}
-<div{{ attributes.addClass('form-managed-file') }}>
+{%
+  set classes = [
+    'js-form-managed-file',
+  ]
+%}
+<div{{ attributes.addClass(classes) }}>
   {{ element }}
 </div>
diff --git a/core/themes/classy/templates/content-edit/file-managed-file.html.twig b/core/themes/classy/templates/content-edit/file-managed-file.html.twig
index 43739be..f639237 100644
--- a/core/themes/classy/templates/content-edit/file-managed-file.html.twig
+++ b/core/themes/classy/templates/content-edit/file-managed-file.html.twig
@@ -10,6 +10,12 @@
  * @see template_preprocess_file_managed_file()
  */
 #}
-<div{{ attributes.addClass('form-managed-file') }}>
+{%
+  set classes = [
+    'js-form-managed-file',
+    'form-managed-file',
+  ]
+%}
+<div{{ attributes.addClass(classes) }}>
   {{ element }}
 </div>