redmine/app/views/users/edit_membership.js.erb

<% if @membership.valid? %>
  $('#tab-content-memberships').html('<%= escape_javascript(render :partial => 'users/memberships') %>');
  $("#member-<%= @membership.id %>").effect("highlight");
<% else %>
  alert('<%= raw(escape_javascript(l(:notice_failed_to_save_members, :errors => @membership.errors.full_messages.join(', ')))) %>');
<% end %>