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<html>
<head>
    <meta charset="utf-8"/>
    <title>隐藏和显示二维码的HTML代码</title>
</head>
<body>
    <h1>隐藏和显示二维码的HTML代码</h1>
    <p>本页面展示了如何在HTML中实现隐藏和显示二维码。以下是示例代码：</p>
    <div id="qrcode" style="display:none">
        <img src="https://www.example.com/qrcode.jpg"/>
    </div>
    <button onclick="toggleQRCode()">显示/隐藏二维码</button>
    <script>
        function toggleQRCode() {
            var qrcodeDiv = document.getElementById("qrcode");
            if (qrcodeDiv.style.display === 'none') {
                qrcodeDiv.style.display = 'block';
            } else {
                qrcodeDiv.style.display = 'none';
            }
        }
    </script>
</body>
</html>