首先js脚本如下↓

<script type="text/javascript">
     function copyArticle(event){
        const range = document.createRange();
        range.selectNode(document.getElementById('copy_p'));

        const selection = window.getSelection();
        if(selection.rangeCount > 0) selection.removeAllRanges();
        selection.addRange(range);

        document.execCommand('copy');
        alert('复制成功');
    }       
    document.getElementById('copy').addEventListener('click', copyArticle, false);
</script>

别忘了加上下面的内容！

 <span id="copy_p" style="font-weight:bold;">这里是需要复制的内容！</span>
 <button id="copy">点击这个按钮复制</button>

完整示例代码↓

<!DOCTYPE html>
<html>
<head>
    
    <meta charset="utf-8">
    <meta content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0,user-scalable=no" name="viewport" id="viewport">
    <style type="text/css">
    </style>
</head>
    <body>
        
                <span id="copy_p" style="font-weight:bold;">测试1123312</span>
                <button id="copy">复制</button>
       
    </body>
</html>
<script type="text/javascript">
     function copyArticle(event){
        const range = document.createRange();
        range.selectNode(document.getElementById('copy_p'));

        const selection = window.getSelection();
        if(selection.rangeCount > 0) selection.removeAllRanges();
        selection.addRange(range);

        document.execCommand('copy');
        alert('复制成功');
    }       
    document.getElementById('copy').addEventListener('click', copyArticle, false);
</script>