function copyUrl2()

{

var Url2=document.getElementById("biao1");

Url2.select(); // 选择需要复制内容的对象

document.execCommand("Copy"); // 执行浏览器复制命令

alert("已复制好，可贴粘。");

}

</script>

<textarea cols="20" rows="10" id="biao1">用户定义的代码区域</textarea>

<input type="button" onClick="copyUrl2()" value="点击复制代码" />

 <div class="top">

            <div class="copytxt" style="opacity:0;">13162087765</div>

            <div class="txt">

                <div class="box">请添加微信13162087765</div>

                <button class="btn">复制微信号</button>

            </div>

 </div>

function copyArticle(event) {

        const range = document.createRange();

        range.selectNode(document.querySelector(".copytxt"));

        const selection = window.getSelection();

        if(selection.rangeCount > 0) selection.removeAllRanges();

        selection.addRange(range);

        document.execCommand('Copy');

        alert("复制成功！");

    }

    document.querySelector(".btn").addEventListener('click', copyArticle, false);