Javascript 在引导中的悬停事件上显示滚动时，在下拉列表中显示滚动

我想用滚动条显示下拉列表，下面是JSFIDLE的链接。我想一次显示10条记录，然后下拉菜单必须显示滚动条。请帮我解决问题。谢谢

Css:

HTML

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这将是答案。试试看。我用这个做我的网页。谢谢如果这是你的答案。请让我知道。我不再回答这个问题了。我没有面临滚动的问题-

body {
    padding-top: 60px;
    padding-bottom: 40px;
}

.sidebar-nav {
    padding: 9px 0;
}

.dropdown-menu .sub-menu {
    left: 100%;
    position: absolute;
    top: 0;
    visibility: hidden;
    margin-top: -1px;
}

.dropdown-menu li:hover .sub-menu {
    visibility: visible;
}

.dropdown:hover .dropdown-menu {
    display: block;
}

.nav-tabs .dropdown-menu, .nav-pills .dropdown-menu, .navbar .dropdown-menu {
    margin-top: 0;
}

.navbar .sub-menu:before {
    border-bottom: 7px solid transparent;
    border-left: none;
    border-right: 7px solid rgba(0, 0, 0, 0.2);
    border-top: 7px solid transparent;
    left: -7px;
    top: 10px;
}
.navbar .sub-menu:after {
    border-top: 6px solid transparent;
    border-left: none;
    border-right: 6px solid #fff;
    border-bottom: 6px solid transparent;
    left: 10px;
    top: 11px;
    left: -6px;
}

<div class="navbar navbar-fixed-top">
  <div class="navbar-inner">
      <div class="container-fluid">
        <a data-target=".nav-collapse" data-toggle="collapse" class="btn btn-navbar">
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
        </a>
        <a href="#" class="brand">Project name</a>
        <div class="nav-collapse">
          <ul class="nav">
            <li class="active"><a href="#">Home</a></li>
            <li><a href="#">Link</a></li>
            <li><a href="#">Link</a></li>
            <li><a href="#">Link</a></li>
            <li class="dropdown">
              <a data-toggle="dropdown" class="dropdown-toggle" href="#">Dropdown <b class="caret"></b></a>
              <ul class="dropdown-menu">
                <li>

                    <ul class="dropdown-menu sub-menu">
                        <li><a href="#">Action</a></li>
                        <li><a href="#">Another action</a></li>
                        <li><a href="#">Something else here</a></li>
                        <li class="divider"></li>
                        <li class="nav-header">Nav header</li>
                        <li><a href="#">Separated link</a></li>
                        <li><a href="#">One more separated link</a></li>
                    </ul>
                </li>
                <li><a href="#">Another action</a></li>
                <li><a href="#">Something else here</a></li>
                <li class="divider"></li>
                <li class="nav-header">Nav header</li>
                <li><a href="#">Separated link</a></li>
                <li><a href="#">One more separated link</a></li>
              </ul>
            </li>
          </ul>
          <form action="" class="navbar-search pull-left">
            <input type="text" placeholder="Search" class="search-query span2">
          </form>
          <ul class="nav pull-right">
            <li><a href="#">Link</a></li>
            <li class="divider-vertical"></li>
            <li class="dropdown">
              <a class="#" href="#">Menu</a>
            </li>
          </ul>
        </div><!-- /.nav-collapse -->
      </div>
  </div>
</div>

<hr>

<ul class="nav nav-pills">
<li class="active"><a href="#">Regular link</a></li>
<li class="dropdown">
  <a href="#" data-toggle="dropdown" class="dropdown-toggle">Dropdown <b class="caret"></b></a>
  <ul class="dropdown-menu" id="menu1">
    <li>
        <a href="#">2-level Menu <i class="icon-arrow-right"></i></a>
        <ul class="dropdown-menu sub-menu">
            <li><a href="#">Action</a></li>
            <li><a href="#">Another action</a></li>
            <li><a href="#">Something else here</a></li>
            <li class="divider"></li>
            <li class="nav-header">Nav header</li>
            <li><a href="#">Separated link</a></li>
            <li><a href="#">One more separated link</a></li>
        </ul>
    </li>
    <li><a href="#">Another action</a></li>
    <li><a href="#">Something else here</a></li>
    <li class="divider"></li>
    <li><a href="#">Separated link</a></li>
  </ul>
</li>
<li class="dropdown">
  <a href="#">Menu</a>
</li>
<li class="dropdown">
  <a href="#">Menu</a>
</li>
</ul>