Changed data-rails-type to data-js-type

actionpack/lib/action_view/helpers/ajax_helper.rb

@@ -102,7 +102,7 @@ def observe_field(name, options = {})
         options[:name] = name
 
         <<-SCRIPT
-        <script type="application/json" data-rails-type="observe_field">
+        <script type="application/json" data-js-type="observe_field">
         //<![CDATA[
           #{options.to_json}
         // ]]>

actionpack/test/javascript/ajax_test.rb

@@ -354,7 +354,7 @@ def field(options = {})
 
   test "basic" do
     assert_html field,
-      %w(script type="application/json" data-rails-type="observe_field")
+      %w(script type="application/json" data-js-type="observe_field")
   end
 
   test "using a url string" do