if($('nav>.smart-nav>li').is('.active')){ $('.nav-second').addClass('in'); }
<script src=“ https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js “></script> <导航> <ul class=“nav-smart-nav”> <li>仪表板</a></li> <li class=“active”> <a data-toggle=“collapse”aria-expanded=“false”class=“colladed”> 管理员门户</span> </a> <ul id=“”class=“nav-nav-second collapse”aria-expanded=“false”> <li>仪表板</a></li> <li><a href=“activity.html”>客户报告</a></li> </ul> </li> <li> <a data-toggle=“collapse”aria-expanded=“false”class=“colladed”> 支持</span> </a> <ul id=“”class=“nav-nav-second collapse”aria-expanded=“false”> <li>日志</a></li> </ul> </li> </ul> </nav>