我将Bootstrap 4用于带有下拉菜单的可折叠侧边栏。

<nav id="sidebar">
    <ul class="list-unstyled components">
        <li><a href="dashboard.html">Admin Dashboard</a></li>
        <li><a href="#homeSubmenu" data-toggle="collapse" aria-expanded="false" class="dropdown-toggle">Home</a>
            <ul class="collapse list-unstyled" id="homeSubmenu">
                <li>
                    <a href="#">Home 1</a>
                </li>
                <li>
                    <a href="#">Home 2</a>
                </li>
                <li>
                    <a href="#">Home 3</a>
                </li>
            </ul>
        </li>
        <li><a href="#pageSubmenu" data-toggle="collapse" aria-expanded="false" class="dropdown-toggle">Pages</a>
            <ul class="collapse list-unstyled" id="pageSubmenu">
                <li>
                    <a href="#">Page 1</a>
                </li>
                <li>
                    <a href="#">Page 2</a>
                </li>
                <li>
                    <a href="#">Page 3</a>
                </li>
            </ul>
        </li>
        <li><a href="#usersSubmenu" data-toggle="collapse" aria-expanded="false" class="dropdown-toggle">Users</a>
            <ul class="collapse list-unstyled" id="usersSubmenu">
                <li>
                    <a href="users.html">List Users</a>
                </li>
                <li>
                    <a href="users_add.html">Add New User</a>
                </li>
            </ul>
        </li>
        <li><a href="general_settings.html">General Settings</a></li>
        <li>
            <a href="profile.html">My Profile</a>
        </li>
        <li>
            <a href="logout.php">Log Out</a>
        </li>
    </ul>
</nav>

如果用户单击（例如）第一个下拉菜单中的Home 2，有没有办法使该页面上的下拉菜单保持打开状态？当用户查看Home 2时，整个HOME下拉列表应保持打开状态。

谢谢！ 里克