Prevent ES Module processing from affecting non-RailsAdmin assets

Refs. #3488

Author: mshibuya

lib/rails_admin/engine.rb

@@ -43,8 +43,8 @@ class Engine < Rails::Engine
           rails_admin/application.css
         ]
         app.config.assets.paths << RailsAdmin::Engine.root.join('src')
-        require 'rails_admin/support/esmodule_preprocessor'
-        Sprockets.register_preprocessor 'application/javascript', RailsAdmin::ESModulePreprocessor
+        require 'rails_admin/support/es_module_processor'
+        Sprockets.register_bundle_processor 'application/javascript', RailsAdmin::Support::ESModuleProcessor
       when :importmap
         self.importmap = Importmap::Map.new.draw(app.root.join('config/importmap.rails_admin.rb'))
       end

lib/rails_admin/support/es_module_processor.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module RailsAdmin
+  module Support
+    class ESModuleProcessor
+      def self.instance
+        @instance ||= new
+      end
+
+      def self.call(input)
+        instance.call(input)
+      end
+
+      def initialize; end
+
+      def call(input)
+        return unless input[:name] == 'rails_admin/application'
+
+        input[:data].gsub(/^((?:import|export) .+)$/) { "// #{Regexp.last_match(1)}" }
+      end
+    end
+  end
+end

lib/rails_admin/support/esmodule_preprocessor.rb

@@ -10,6 +10,5 @@
 // WARNING: THE FIRST BLANK LINE MARKS THE END OF WHAT'S TO BE PROCESSED, ANY BLANK LINE SHOULD
 // GO AFTER THE REQUIRES BELOW.
 //
-//= require rails-ujs
+//= require rails-ujs.esm
 //= require turbo
-//= require_tree .

spec/dummy_app/app/assets/javascripts/application.js

@@ -0,0 +1 @@
+<%= depend_on_asset('rails-ujs').to_s.gsub(/context = this/, 'context = (this || globalThis)') %>

spec/dummy_app/app/assets/javascripts/rails-ujs.esm.js.erb

@@ -9,7 +9,7 @@
     <%= javascript_importmap_tags %>
   <% else %>
     <%= stylesheet_link_tag    "application", media: "all" %>
-    <%= javascript_include_tag "application" %>
+    <%= javascript_include_tag "application", type: 'module' %>
   <% end %>
   <%= csrf_meta_tags %>
 </head>

spec/dummy_app/app/views/layouts/application.html.erb

@@ -1,4 +1,4 @@
-export default {
+var I18n = {
   locale: null,
   translations: null,
   init(locale, translations) {
@@ -14,3 +14,5 @@ export default {
     return this.translations[key] || humanize;
   },
 };
+
+export { I18n as default };