javascript实现在线运行代码功能

<textarea name="t11" id="t11" rows="12" cols="95">
<!--里面写要运行的代码开始-->
<!--里面写要运行的代码结束-->
</textarea>
<br>
<input type="button" value="运行代码" style="border-left:1px solid #B1B4CD;border-right:1px solid #494D74;border-top:1px solid #B1B4CD;;border-bottom:1px solid #494D74;background:#696D81;color:#FFFFFF;" onClick="runCode(document.getElementById('t11'))">
<script language="javascript">
function runCode(obj)
{
   var winname = window.open('', "_blank", '');
   winname.document.open('text/html', 'replace');
   winname.opener = null // 防止代码对论谈页面修改
   winname.document.write(obj.value);
   winname.document.close();
}
</script>