js 内容复制 读取

<script language="javascript">
//读取剪贴板中内容
function readTxt()
{
alert(window.clipboardData.getData("text"));
}
//复制文本框内容 到剪贴板
function setTxt()
{
var t=document.getElementById("txt");
t.select();
window.clipboardData.setData('text',t.value);
}
//复制span内容 到剪贴板
function setTxt1()
{
var t=document.getElementById("url");
var txt=t.innerText;
window.clipboardData.setData('text',txt);
}
</script>
<input name="txt" value="测试">
<input type="button" value="复制" onclick="setTxt()">
<input type="button" value="读取" onclick="readTxt()">
<span id="url">www.07tg.com</span> <input type="button" value="复制" onclick="setTxt1()">