diff --git a/core/modules/book/book.libraries.yml b/core/modules/book/book.libraries.yml
index d2bd52d..7ba12c4 100644
--- a/core/modules/book/book.libraries.yml
+++ b/core/modules/book/book.libraries.yml
@@ -1,7 +1,7 @@
 drupal.book:
   version: VERSION
   js:
-    book.js: {}
+    js/book.js: {}
   dependencies:
     - core/jquery
     - core/drupal
diff --git a/core/modules/book/book.js b/core/modules/book/js/book.js
similarity index 100%
rename from core/modules/book/book.js
rename to core/modules/book/js/book.js
diff --git a/core/modules/color/color.libraries.yml b/core/modules/color/color.libraries.yml
index b2eb8d6..57656de 100644
--- a/core/modules/color/color.libraries.yml
+++ b/core/modules/color/color.libraries.yml
@@ -1,7 +1,7 @@
 drupal.color:
   version: VERSION
   js:
-    color.js: {}
+    js/color.js: {}
   dependencies:
     - core/jquery
     - core/drupal
@@ -12,7 +12,7 @@ drupal.color:
 drupal.color.preview:
   version: VERSION
   js:
-    preview.js: {}
+    js/preview.js: {}
   dependencies:
     - core/jquery
     - core/drupal
diff --git a/core/modules/color/color.js b/core/modules/color/js/color.js
similarity index 100%
rename from core/modules/color/color.js
rename to core/modules/color/js/color.js
diff --git a/core/modules/color/preview.js b/core/modules/color/js/preview.js
similarity index 100%
rename from core/modules/color/preview.js
rename to core/modules/color/js/preview.js
diff --git a/core/modules/comment/comment.libraries.yml b/core/modules/comment/comment.libraries.yml
index d19ff93..113cb25 100644
--- a/core/modules/comment/comment.libraries.yml
+++ b/core/modules/comment/comment.libraries.yml
@@ -1,7 +1,7 @@
 drupal.comment:
   version: VERSION
   js:
-    comment-entity-form.js: {}
+    js/comment-entity-form.js: {}
   dependencies:
     - core/jquery
     - core/drupal
diff --git a/core/modules/comment/comment-entity-form.js b/core/modules/comment/js/comment-entity-form.js
similarity index 100%
rename from core/modules/comment/comment-entity-form.js
rename to core/modules/comment/js/comment-entity-form.js
diff --git a/core/modules/content_translation/content_translation.libraries.yml b/core/modules/content_translation/content_translation.libraries.yml
index 3dd1ce0..f7c761b 100644
--- a/core/modules/content_translation/content_translation.libraries.yml
+++ b/core/modules/content_translation/content_translation.libraries.yml
@@ -1,7 +1,7 @@
 drupal.content_translation.admin:
   version: VERSION
   js:
-    content_translation.admin.js: {}
+    js/content_translation.admin.js: {}
   css:
     theme:
       css/content_translation.admin.css: {}
diff --git a/core/modules/content_translation/content_translation.admin.js b/core/modules/content_translation/js/content_translation.admin.js
similarity index 100%
rename from core/modules/content_translation/content_translation.admin.js
rename to core/modules/content_translation/js/content_translation.admin.js
diff --git a/core/modules/field_ui/field_ui.libraries.yml b/core/modules/field_ui/field_ui.libraries.yml
index 4add558..783aba7 100644
--- a/core/modules/field_ui/field_ui.libraries.yml
+++ b/core/modules/field_ui/field_ui.libraries.yml
@@ -1,7 +1,7 @@
 drupal.field_ui:
   version: VERSION
   js:
-    field_ui.js: {}
+    js/field_ui.js: {}
   css:
     theme:
       css/field_ui.admin.css: {}
diff --git a/core/modules/field_ui/field_ui.js b/core/modules/field_ui/js/field_ui.js
similarity index 100%
rename from core/modules/field_ui/field_ui.js
rename to core/modules/field_ui/js/field_ui.js
diff --git a/core/modules/file/file.libraries.yml b/core/modules/file/file.libraries.yml
index c44af55..c929ede 100644
--- a/core/modules/file/file.libraries.yml
+++ b/core/modules/file/file.libraries.yml
@@ -1,7 +1,7 @@
 drupal.file:
   version: VERSION
   js:
-    file.js: {}
+    js/file.js: {}
   css:
     theme:
       css/file.admin.css: {}
diff --git a/core/modules/file/file.js b/core/modules/file/js/file.js
similarity index 100%
rename from core/modules/file/file.js
rename to core/modules/file/js/file.js
diff --git a/core/modules/filter/filter.libraries.yml b/core/modules/filter/filter.libraries.yml
index 91aea0b..3a25dd7 100644
--- a/core/modules/filter/filter.libraries.yml
+++ b/core/modules/filter/filter.libraries.yml
@@ -1,7 +1,7 @@
 drupal.filter.admin:
   version: VERSION
   js:
-    filter.admin.js: {}
+    js/filter.admin.js: {}
   css:
     theme:
       css/filter.admin.css: {}
@@ -14,7 +14,7 @@ drupal.filter.admin:
 drupal.filter.filter_html.admin:
   version: VERSION
   js:
-    filter.filter_html.admin.js: {}
+    js/filter.filter_html.admin.js: {}
   dependencies:
     - core/jquery
     - core/jquery.once
@@ -23,7 +23,7 @@ drupal.filter.filter_html.admin:
 drupal.filter:
   version: VERSION
   js:
-    filter.js: {}
+    js/filter.js: {}
   css:
     theme:
       # @todo Misnomer: Does not contain administrative styles.
diff --git a/core/modules/filter/filter.admin.js b/core/modules/filter/js/filter.admin.js
similarity index 100%
rename from core/modules/filter/filter.admin.js
rename to core/modules/filter/js/filter.admin.js
diff --git a/core/modules/filter/filter.filter_html.admin.js b/core/modules/filter/js/filter.filter_html.admin.js
similarity index 100%
rename from core/modules/filter/filter.filter_html.admin.js
rename to core/modules/filter/js/filter.filter_html.admin.js
diff --git a/core/modules/filter/filter.js b/core/modules/filter/js/filter.js
similarity index 100%
rename from core/modules/filter/filter.js
rename to core/modules/filter/js/filter.js
diff --git a/core/modules/language/language.admin.js b/core/modules/language/js/language.admin.js
similarity index 100%
rename from core/modules/language/language.admin.js
rename to core/modules/language/js/language.admin.js
diff --git a/core/modules/language/language.libraries.yml b/core/modules/language/language.libraries.yml
index 0c4cc8c..c2cef78 100644
--- a/core/modules/language/language.libraries.yml
+++ b/core/modules/language/language.libraries.yml
@@ -1,7 +1,7 @@
 drupal.language.admin:
   version: VERSION
   js:
-    language.admin.js: {}
+    js/language.admin.js: {}
   css:
     theme:
       css/language.admin.css: {}
diff --git a/core/modules/locale/locale.admin.js b/core/modules/locale/js/locale.admin.js
similarity index 100%
rename from core/modules/locale/locale.admin.js
rename to core/modules/locale/js/locale.admin.js
diff --git a/core/modules/locale/locale.bulk.js b/core/modules/locale/js/locale.bulk.js
similarity index 100%
rename from core/modules/locale/locale.bulk.js
rename to core/modules/locale/js/locale.bulk.js
diff --git a/core/modules/locale/locale.datepicker.js b/core/modules/locale/js/locale.datepicker.js
similarity index 100%
rename from core/modules/locale/locale.datepicker.js
rename to core/modules/locale/js/locale.datepicker.js
diff --git a/core/modules/locale/locale.libraries.yml b/core/modules/locale/locale.libraries.yml
index 9711d01..0dc3140 100644
--- a/core/modules/locale/locale.libraries.yml
+++ b/core/modules/locale/locale.libraries.yml
@@ -1,7 +1,7 @@
 drupal.locale.admin:
   version: VERSION
   js:
-    locale.admin.js: {}
+    js/locale.admin.js: {}
   css:
     component:
       css/locale.admin.css: {}
@@ -14,7 +14,7 @@ drupal.locale.admin:
 drupal.locale.datepicker:
   version: VERSION
   js:
-    locale.datepicker.js: {}
+    js/locale.datepicker.js: {}
   dependencies:
     - core/jquery
     - core/drupal
@@ -27,4 +27,4 @@ translations:
     # This file does not actually exist; it's a placeholder file that will be
     # overriden by locale_js_alter(), to use the file that contains the actual
     # translations, for the language used in the current request.
-    locale.translation.js: {}
+    js/locale.translation.js: {}
diff --git a/core/modules/locale/locale.module b/core/modules/locale/locale.module
index 6bdc5aa..b2bad2b 100644
--- a/core/modules/locale/locale.module
+++ b/core/modules/locale/locale.module
@@ -492,7 +492,7 @@ function locale_js_alter(&$javascript, AttachedAssetsInterface $assets) {
   foreach ($javascript as $item) {
     if (isset($item['type']) && $item['type'] == 'file') {
       // Ignore the JS translation placeholder file.
-      if ($item['data'] === 'core/modules/locale/locale.translation.js') {
+      if ($item['data'] === 'core/modules/locale/js/locale.translation.js') {
         continue;
       }
       $files[] = $item['data'];
@@ -500,7 +500,7 @@ function locale_js_alter(&$javascript, AttachedAssetsInterface $assets) {
   }
 
   // Replace the placeholder file with the actual JS translation file.
-  $placeholder_file = 'core/modules/locale/locale.translation.js';
+  $placeholder_file = 'core/modules/locale/js/locale.translation.js';
   if (isset($javascript[$placeholder_file])) {
     if ($translation_file = locale_js_translate($files)) {
       $js_translation_asset = &$javascript[$placeholder_file];
diff --git a/core/modules/locale/src/Tests/LocaleJavascriptTranslationTest.php b/core/modules/locale/src/Tests/LocaleJavascriptTranslationTest.php
index 1436527..a78c32c 100644
--- a/core/modules/locale/src/Tests/LocaleJavascriptTranslationTest.php
+++ b/core/modules/locale/src/Tests/LocaleJavascriptTranslationTest.php
@@ -26,7 +26,7 @@ class LocaleJavascriptTranslationTest extends WebTestBase {
   public static $modules = array('locale');
 
   public function testFileParsing() {
-    $filename = drupal_get_path('module', 'locale') . '/tests/locale_test.js';
+    $filename = drupal_get_path('module', 'locale') . '/tests/js/locale_test.js';
 
     // Parse the file to look for source strings.
     _locale_parse_js_file($filename);
@@ -131,7 +131,7 @@ public function testLocaleTranslationJsDependencies() {
       ->getStrings(array(
         'source' => 'Show description',
         'type' => 'javascript',
-        'name' => 'core/modules/locale/locale.admin.js',
+        'name' => 'core/modules/locale/js/locale.admin.js',
       ));
     $string = $strings[0];
 
diff --git a/core/modules/locale/src/Tests/LocaleLibraryAlterTest.php b/core/modules/locale/src/Tests/LocaleLibraryAlterTest.php
index 682af83..4f2b62d 100644
--- a/core/modules/locale/src/Tests/LocaleLibraryAlterTest.php
+++ b/core/modules/locale/src/Tests/LocaleLibraryAlterTest.php
@@ -34,6 +34,6 @@ public function testLibraryAlter() {
     $assets = new AttachedAssets();
     $assets->setLibraries(['core/jquery.ui.datepicker']);
     $js_assets = $this->container->get('asset.resolver')->getJsAssets($assets, FALSE)[1];
-    $this->assertTrue(array_key_exists('core/modules/locale/locale.datepicker.js', $js_assets), 'locale.datepicker.js added to scripts.');
+    $this->assertTrue(array_key_exists('core/modules/locale/js/locale.datepicker.js', $js_assets), 'locale.datepicker.js added to scripts.');
   }
 }
diff --git a/core/modules/locale/tests/locale_test.js b/core/modules/locale/tests/js/locale_test.js
similarity index 100%
rename from core/modules/locale/tests/locale_test.js
rename to core/modules/locale/tests/js/locale_test.js
diff --git a/core/modules/menu_ui/menu_ui.admin.js b/core/modules/menu_ui/js/menu_ui.admin.js
similarity index 100%
rename from core/modules/menu_ui/menu_ui.admin.js
rename to core/modules/menu_ui/js/menu_ui.admin.js
diff --git a/core/modules/menu_ui/menu_ui.js b/core/modules/menu_ui/js/menu_ui.js
similarity index 100%
rename from core/modules/menu_ui/menu_ui.js
rename to core/modules/menu_ui/js/menu_ui.js
diff --git a/core/modules/menu_ui/menu_ui.libraries.yml b/core/modules/menu_ui/menu_ui.libraries.yml
index c5f9594..544ae9b 100644
--- a/core/modules/menu_ui/menu_ui.libraries.yml
+++ b/core/modules/menu_ui/menu_ui.libraries.yml
@@ -1,7 +1,7 @@
 drupal.menu_ui:
   version: VERSION
   js:
-    menu_ui.js: {}
+    js/menu_ui.js: {}
   dependencies:
     - core/jquery
     - core/drupal
@@ -10,7 +10,7 @@ drupal.menu_ui:
 drupal.menu_ui.admin:
   version: VERSION
   js:
-    menu_ui.admin.js: {}
+    js/menu_ui.admin.js: {}
   dependencies:
     - core/jquery
     - core/drupal
diff --git a/core/modules/node/content_types.js b/core/modules/node/js/content_types.js
similarity index 100%
rename from core/modules/node/content_types.js
rename to core/modules/node/js/content_types.js
diff --git a/core/modules/node/node.js b/core/modules/node/js/node.js
similarity index 100%
rename from core/modules/node/node.js
rename to core/modules/node/js/node.js
diff --git a/core/modules/node/node.preview.js b/core/modules/node/js/node.preview.js
similarity index 100%
rename from core/modules/node/node.preview.js
rename to core/modules/node/js/node.preview.js
diff --git a/core/modules/node/node.libraries.yml b/core/modules/node/node.libraries.yml
index 22c93ac..e89ebd4 100644
--- a/core/modules/node/node.libraries.yml
+++ b/core/modules/node/node.libraries.yml
@@ -4,7 +4,7 @@ drupal.node:
     layout:
       css/node.module.css: {}
   js:
-    node.js: {}
+    js/node.js: {}
   dependencies:
     - core/jquery
     - core/drupal
@@ -17,7 +17,7 @@ drupal.node.preview:
     theme:
       css/node.preview.css: {}
   js:
-    node.preview.js: {}
+    js/node.preview.js: {}
   dependencies:
     - core/jquery
     - core/jquery.once
@@ -27,7 +27,7 @@ drupal.node.preview:
 drupal.content_types:
   version: VERSION
   js:
-    content_types.js: {}
+    js/content_types.js: {}
   dependencies:
     - core/jquery
     - core/drupal
diff --git a/core/modules/path/path.js b/core/modules/path/js/path.js
similarity index 100%
rename from core/modules/path/path.js
rename to core/modules/path/js/path.js
diff --git a/core/modules/path/path.libraries.yml b/core/modules/path/path.libraries.yml
index 2ce29a5..69170f2 100644
--- a/core/modules/path/path.libraries.yml
+++ b/core/modules/path/path.libraries.yml
@@ -1,7 +1,7 @@
 drupal.path:
   version: VERSION
   js:
-    path.js: {}
+    js/path.js: {}
   dependencies:
     - core/jquery
     - core/drupal
diff --git a/core/modules/simpletest/simpletest.js b/core/modules/simpletest/js/simpletest.js
similarity index 100%
rename from core/modules/simpletest/simpletest.js
rename to core/modules/simpletest/js/simpletest.js
diff --git a/core/modules/simpletest/simpletest.libraries.yml b/core/modules/simpletest/simpletest.libraries.yml
index 7bcbc07..7c6e714 100644
--- a/core/modules/simpletest/simpletest.libraries.yml
+++ b/core/modules/simpletest/simpletest.libraries.yml
@@ -1,7 +1,7 @@
 drupal.simpletest:
   version: VERSION
   js:
-    simpletest.js: {}
+    js/simpletest.js: {}
   css:
     component:
       css/simpletest.module.css: {}
diff --git a/core/modules/statistics/statistics.js b/core/modules/statistics/js/statistics.js
similarity index 100%
rename from core/modules/statistics/statistics.js
rename to core/modules/statistics/js/statistics.js
diff --git a/core/modules/statistics/src/Tests/StatisticsLoggingTest.php b/core/modules/statistics/src/Tests/StatisticsLoggingTest.php
index cc792cd..e790cc7 100644
--- a/core/modules/statistics/src/Tests/StatisticsLoggingTest.php
+++ b/core/modules/statistics/src/Tests/StatisticsLoggingTest.php
@@ -73,7 +73,7 @@ function testLogging() {
     $path = 'node/' . $this->node->id();
     $module_path = drupal_get_path('module', 'statistics');
     $stats_path = $base_url . '/' . $module_path . '/statistics.php';
-    $expected_library = $module_path . '/statistics.js';
+    $expected_library = $module_path . '/js/statistics.js';
     $expected_settings = '"statistics":{"data":{"nid":"' . $this->node->id() . '"}';
 
     // Verify that logging scripts are not found on a non-node page.
diff --git a/core/modules/statistics/statistics.libraries.yml b/core/modules/statistics/statistics.libraries.yml
index 76c58a1..01769f1 100644
--- a/core/modules/statistics/statistics.libraries.yml
+++ b/core/modules/statistics/statistics.libraries.yml
@@ -1,7 +1,7 @@
 drupal.statistics:
   version: VERSION
   js:
-    statistics.js: {}
+    js/statistics.js: {}
   dependencies:
     - core/jquery
     - core/drupal
diff --git a/core/modules/system/system.js b/core/modules/system/js/system.js
similarity index 100%
rename from core/modules/system/system.js
rename to core/modules/system/js/system.js
diff --git a/core/modules/system/system.modules.js b/core/modules/system/js/system.modules.js
similarity index 100%
rename from core/modules/system/system.modules.js
rename to core/modules/system/js/system.modules.js
diff --git a/core/modules/system/src/Tests/Common/AttachedAssetsTest.php b/core/modules/system/src/Tests/Common/AttachedAssetsTest.php
index 3251305..2d3803d 100644
--- a/core/modules/system/src/Tests/Common/AttachedAssetsTest.php
+++ b/core/modules/system/src/Tests/Common/AttachedAssetsTest.php
@@ -403,7 +403,7 @@ function testAlter() {
     $js = $this->assetResolver->getJsAssets($assets, FALSE)[1];
     $js_render_array = \Drupal::service('asset.js.collection_renderer')->render($js);
     $rendered_js = $this->renderer->render($js_render_array);
-    $this->assertTrue(strpos($rendered_js, 'simpletest.js') < strpos($rendered_js, 'core/misc/tableselect.js'), 'Altering JavaScript weight through the alter hook.');
+    $this->assertTrue(strpos($rendered_js, 'simpletest.js') > strpos($rendered_js, 'core/misc/tableselect.js'), 'Altering JavaScript weight through the alter hook.');
   }
 
   /**
diff --git a/core/modules/system/system.libraries.yml b/core/modules/system/system.libraries.yml
index 34c90dd..c0a55f4 100644
--- a/core/modules/system/system.libraries.yml
+++ b/core/modules/system/system.libraries.yml
@@ -29,7 +29,7 @@ maintenance:
 drupal.system:
   version: VERSION
   js:
-    system.js: {}
+    js/system.js: {}
   dependencies:
     - core/jquery
     - core/drupal
@@ -39,7 +39,7 @@ drupal.system:
 drupal.system.modules:
   version: VERSION
   js:
-    system.modules.js: {}
+    js/system.modules.js: {}
   dependencies:
     - core/jquery
     - core/drupal
diff --git a/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.js b/core/modules/system/tests/modules/twig_theme_test/js/twig_theme_test.js
similarity index 100%
rename from core/modules/system/tests/modules/twig_theme_test/twig_theme_test.js
rename to core/modules/system/tests/modules/twig_theme_test/js/twig_theme_test.js
diff --git a/core/modules/taxonomy/taxonomy.js b/core/modules/taxonomy/js/taxonomy.js
similarity index 100%
rename from core/modules/taxonomy/taxonomy.js
rename to core/modules/taxonomy/js/taxonomy.js
diff --git a/core/modules/taxonomy/taxonomy.libraries.yml b/core/modules/taxonomy/taxonomy.libraries.yml
index 3a7904f..1d4cd9e 100644
--- a/core/modules/taxonomy/taxonomy.libraries.yml
+++ b/core/modules/taxonomy/taxonomy.libraries.yml
@@ -1,7 +1,7 @@
 drupal.taxonomy:
   version: VERSION
   js:
-    taxonomy.js: {}
+    js/taxonomy.js: {}
   css:
     component:
       css/taxonomy.theme.css: {}
diff --git a/core/modules/text/text.js b/core/modules/text/js/text.js
similarity index 100%
rename from core/modules/text/text.js
rename to core/modules/text/js/text.js
diff --git a/core/modules/text/text.libraries.yml b/core/modules/text/text.libraries.yml
index 8e82411..c3b564a 100644
--- a/core/modules/text/text.libraries.yml
+++ b/core/modules/text/text.libraries.yml
@@ -1,7 +1,7 @@
 drupal.text:
   version: VERSION
   js:
-    text.js: {}
+    js/text.js: {}
   dependencies:
     - core/jquery
     - core/jquery.once
diff --git a/core/modules/user/user.js b/core/modules/user/js/user.js
similarity index 100%
rename from core/modules/user/user.js
rename to core/modules/user/js/user.js
diff --git a/core/modules/user/user.permissions.js b/core/modules/user/js/user.permissions.js
similarity index 100%
rename from core/modules/user/user.permissions.js
rename to core/modules/user/js/user.permissions.js
diff --git a/core/modules/user/user.libraries.yml b/core/modules/user/user.libraries.yml
index e11cbfa..afe78cb 100644
--- a/core/modules/user/user.libraries.yml
+++ b/core/modules/user/user.libraries.yml
@@ -1,7 +1,7 @@
 drupal.user:
   version: VERSION
   js:
-    user.js: {}
+    js/user.js: {}
   css:
     component:
       css/user.module.css: {}
@@ -21,7 +21,7 @@ drupal.user.admin:
 drupal.user.permissions:
   version: VERSION
   js:
-    user.permissions.js: {}
+    js/user.permissions.js: {}
   dependencies:
     - core/jquery
     - core/jquery.once
diff --git a/core/modules/views/tests/modules/views_test_data/views_cache.test.js b/core/modules/views/tests/modules/views_test_data/js/views_cache.test.js
similarity index 100%
rename from core/modules/views/tests/modules/views_test_data/views_cache.test.js
rename to core/modules/views/tests/modules/views_test_data/js/views_cache.test.js
diff --git a/core/modules/views/tests/modules/views_test_data/views_test_data.libraries.yml b/core/modules/views/tests/modules/views_test_data/views_test_data.libraries.yml
index 4b4d8a2..88f9f6d 100644
--- a/core/modules/views/tests/modules/views_test_data/views_test_data.libraries.yml
+++ b/core/modules/views/tests/modules/views_test_data/views_test_data.libraries.yml
@@ -3,4 +3,4 @@ test:
     component:
       views_cache.test.css: {}
   js:
-    views_cache.test.js: {}
+    js/views_cache.test.js: {}