app/views/blogit/admin/comments/create.js.erb
var $form = $("form#new_blog_comment");
<% if @comment.save %>
$("#comments").append("<%= escape_javascript(render(@comment)) %>");
$form.get(0).reset();
<% else %>
$form.html("<%= escape_javascript(render(partial:'form', locals: { post: @comment.post, comment: @comment })) %>");
<% end %>