如何在导航栏中添加按钮来显示/隐藏侧边栏，就像在shinydashboard中一样

要在导航栏中添加按钮来显示/隐藏侧边栏，可以使用HTML、CSS和JavaScript来实现。以下是一个简单的示例，展示了如何在导航栏中添加一个按钮，并通过点击该按钮来显示或隐藏侧边栏。

HTML部分

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>导航栏侧边栏示例</title>
    <link rel="stylesheet" href="styles.css">
</head>
<body>
    <nav class="navbar">
        <button id="sidebarToggle" class="sidebar-toggle">☰</button>
        <h1>网站标题</h1>
    </nav>
    <div class="sidebar" id="sidebar">
        <ul>
            <li><a href="#">菜单项1</a></li>
            <li><a href="#">菜单项2</a></li>
            <li><a href="#">菜单项3</a></li>
        </ul>
    </div>
    <main class="content">
        <p>这里是主要内容区域。</p>
    </main>
    <script src="script.js"></script>
</body>
</html>

CSS部分（styles.css）

body {
    margin: 0;
    font-family: Arial, sans-serif;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: #333;
    padding: 10px 20px;
    color: white;
}

.sidebar-toggle {
    background: none;
    border: none;
    color: white;
    font-size: 24px;
    cursor: pointer;
}

.sidebar {
    position: fixed;
    top: 0;
    left: -250px;
    width: 250px;
    height: 100%;
    background-color: #444;
    transition: left 0.3s ease;
}

.sidebar ul {
    list-style-type: none;
    padding: 0;
}

.sidebar ul li a {
    display: block;
    padding: 10px;
    color: white;
    text-decoration: none;
}

.sidebar ul li a:hover {
    background-color: #555;
}

.content {
    margin-left: 0;
    padding: 20px;
    transition: margin-left 0.3s ease;
}

JavaScript部分（script.js）

document.getElementById('sidebarToggle').addEventListener('click', function() {
    const sidebar = document.getElementById('sidebar');
    const content = document.querySelector('.content');
    if (sidebar.style.left === '-250px' || sidebar.style.left === '') {
        sidebar.style.left = '0';
        content.style.marginLeft = '250px';
    } else {
        sidebar.style.left = '-250px';
        content.style.marginLeft = '0';
    }
});