<!-- 顶部导航 -->
<div class="navbar navbar-inverse navbar-fixed-top" role="navigation" id="menu-nav">
 <div class="container">
  <div class="navbar-header">
   <a class="navbar-brand" href="#">XXXXX</a>
  </div>
  <div class="navbar-collapse collapse">
   <ul class="nav navbar-nav">
    <li class="active"><a href="#">首页</a></li>
    <li><a href="#">简述</a></li>
    <li><a href="#" data-toggle="modal" data-target="#about-modal">关于</a></li>
   </ul>
   <ul class="nav navbar-nav" style="margin-left:700px;">
    <li><a href="#" onClick="showLogin()">登录</a></li>
    <li><a href="#" onClick="showRegister()">注册</a></li>
   </ul>
  </div>
 </div>
</div>

<!--选项卡登录和注册-->
<div id="login-register">
<ul class="nav nav-tabs" role="tablist" id="feature-tab">
  <li id="li-login" onClick="setLoginActive()"><a href="#tab-login" role="tab" data-toggle="tab">登录</a></li>
  <li id="li-register" onClick="setRegisterActive()"><a href="#tab-register" role="tab" data-toggle="tab">注册</a></li>
  <button onClick="closeTab()" id="btn-close">X</button>
</ul>

<div class="tab-content">
  <br>
  <div class="tab-pane" id="tab-login">
   <div class="row feature">
    <br><br>
    <form class="form-horizontal" role="form">
     <div class="form-group">
     <label for="inputEmail3" class="col-sm-3 control-label">帐号:</label>
     <div class="col-sm-9">
      <input type="email" class="form-control" id="inputEmail3" 
       placeholder="请输入电子邮箱地址/手机号">
     </div>
     </div>
     <div class="form-group">
     <label for="inputPassword3" class="col-sm-3 control-label">密码:</label>
     <div class="col-sm-9">
      <input type="password" class="form-control" id="inputPassword3"
        placeholder="请输入您的帐号密码">
     </div>
     </div>
     <div class="form-group">
     <div class="col-sm-offset-6 col-sm-6">
      <button type="submit" class="btn btn-primary">登录</button>
     </div>
     </div>
    </form>
   </div>
  </div>
  <div class="tab-pane" id="tab-register">
   <div class="row feature">
    <br>
     <form class="form-horizontal" role="form">
     <div class="form-group">
     <label for="inputEmail3" class="col-sm-3 control-label">帐号:</label>
     <div class="col-sm-9">
      <input type="email" class="form-control" id="inputEmail3" 
       placeholder="请输入电子邮箱地址/手机号">
     </div>
     </div>
     <div class="form-group">
     <label for="inputPassword3" class="col-sm-3 control-label">密码:</label>
     <div class="col-sm-9">
      <input type="password" class="form-control" id="inputPassword3"
        placeholder="请输入您的帐号密码">
     </div>
     </div>
     <div class="form-group">
     <label for="inputPassword3" class="col-sm-3 control-label">密码:</label>
     <div class="col-sm-9">
      <input type="password" class="form-control" id="inputPassword3"
        placeholder="请再输一次密码，确认是否正确">
     </div>
     </div>
     <div class="form-group">
     <div class="col-sm-offset-6 col-sm-6">
      <button type="submit" class="btn btn-primary">注册</button>
     </div>
     </div>
    </form>
   </div>
  </div>
</div>

 function showLogin() //点击顶部导航栏登录按钮，让选项卡先出现登录
 {
   var login_id = document.getElementById("login-register");
   if (login_id.style.display == 'block')
    login_id.style.display = "none";
   setLoginActive(); //选项卡出现登录页面
   login_id.style.display = 'block'; 

 }

 function showRegister() //点击顶部导航栏注册按钮，让选项卡先出现注册
 {
   var register_id = document.getElementById("login-register");
   if (register_id.style.display == 'block')
    register_id.style.display = "none";
   setRegisterActive(); 选项卡出现注册页面
   register_id.style.display = 'block'; 

 }

 function setLoginActive() //在选项卡内部自由切换
 {
  var div_lo = document.getElementById("tab-login");
  var li_lo = document.getElementById("li-login");
  var div_re = document.getElementById("tab-register");
  var li_re = document.getElementById("li-register"); 
  div_re.className = ""; //移除注册框的active，同时移除了该div的所有类
  li_re.className = "";
  div_re.className = "tab-pane"; //不能去掉该类，如果去掉则不能切换
  div_lo.className = "active";
  li_lo.className = "active";

 }

 function setRegisterActive()
 {
  var div_lo = document.getElementById("tab-login");
  var li_lo = document.getElementById("li-login");
  var div_re = document.getElementById("tab-register");
  var li_re = document.getElementById("li-register"); 
  div_lo.className = "";
  li_lo.className = "";
  div_lo.className = "tab-pane";
  div_re.className = "active";
  li_re.className = "active"; 
 }

 function closeTab() //关闭选项卡
 {
  var tab = document.getElementById("login-register"); 
  tab.style.display = "none";
 }