openproject/app/assets/javascripts/settings.js.erb

<%#-- copyright
OpenProject is a project management system.
Copyright (C) 2012-2015 the OpenProject Foundation (OPF)

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License version 3.

OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
Copyright (C) 2006-2013 Jean-Philippe Lang
Copyright (C) 2010-2013 the ChiliProject Team

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

See doc/COPYRIGHT.rdoc for more details.

++#%>

(function($) {
  $(function() {

    $('#settings_session_ttl_enabled').on('change', function(){
      $('#settings_session_ttl_container').toggle($(this).is(':checked'));
    }).trigger('change');


    /** Sync SCM vendor select when enabled SCMs are changed */
    $('[name="settings[enabled_scm][]"]').change(function () {
      var disabled = !this.checked,
        vendor = this.value,
        select = $('#settings_repositories_automatic_managed_vendor'),
        option = select.find('option[value="' + vendor + '"]');

      // Skip non-manageable SCMs
      if (option.length === 0) {
        return;
      }

      option.prop('disabled', disabled);
      if (disabled && option.prop('selected')) {
        select.val('');
      }

    });
  });
}(jQuery));