Use App.Comments module in create.js.erb

app/assets/javascripts/comments.js.coffee

@@ -1,6 +1,13 @@
-
 App.Comments =
 
+  add_response: (parent_id, response_html) ->
+    $(response_html).insertAfter($("#js-comment-form-#{parent_id}"))
+
+  reset_and_hide_form: (id) ->
+    form = $("#js-comment-form-#{id}")
+    form.val('')
+    form.hide()
+
   toggle_form: (id) ->
     $("#js-comment-form-#{id}").toggle()
 

app/views/comments/create.js.erb

@@ -1,4 +1,3 @@
-var form = "#js-comment-form-<%= dom_id(@parent) %>"
-$(form + " #comment_body").val('');
-$(form).hide();
-$("<%= j(render @comment) %>").insertAfter($(form));
+var parent_id = '<%= dom_id(@parent) %>';
+App.Comments.reset_and_hide_form(parent_id);
+App.Comments.add_response(parent_id, "<%= j(render @comment) %>");