js实现点击复制

<script type="text/javascript">
function copyUrl2()
    {
        var Url2=document.getElementById("biao1").innerText;
        var oInput = document.createElement('input');
        oInput.value = Url2;
        document.body.appendChild(oInput);
        oInput.select(); // 选择对象
        document.execCommand("Copy"); // 执行浏览器复制命令
        oInput.className = 'oInput';
        oInput.style.display='none';
        alert('复制成功');
    }
</script>
<div cols="20" id="biao1">12345678</div>
<input type="button" onClick="copyUrl2()" value="点击复制代码" />