问Bootstrap 3导航栏切换不起作用

EN

<!-- Navigation -->
<nav class="navbar navbar-inverse navbar-fixed-top">
    <div class="container">
        <!-- Brand and toggle get grouped for better mobile display -->
        <div class="navbar-header page-scroll">
            <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#navbar-collapse">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="#page-top">Name</a>
        </div>

        <!-- Collect the nav links, forms, and other content for toggling -->
        <div class="collapse navbar-collapse" id="navbar-collapse">
            <ul class="nav navbar-nav navbar-right">
                <li class="hidden">
                    <a href="#page-top"></a>
                </li>
                <li class="page-scroll">
                    <a href="#portfolio">Home</a>
                </li>
                <li class="page-scroll">
                    <a href="#about">Downloads</a>
                </li>
                <li class="page-scroll">
                    <a href="#contact">Contact</a>
                </li>
            </ul>
        </div>
        <!-- /.navbar-collapse -->
    </div>
    <!-- /.container-fluid -->
</nav>

<!-- jQuery -->
<script src="js/jquery.js" />

<!-- Latest compiled and minified JavaScript -->
<script src="js/bootstrap.js" />