js点击复制文本

<input type="text" id="div" />
<button id="btn">点击复制文本框内容</button>
<script type="text/javascript">
document.getElementById("btn").addEventListener("click",clickone,false);
function clickone(){
var Url2 = document.getElementById("div");
Url2.select();
document.execCommand("Copy");
console.log("已经粘贴完成");

}
</script>