[JavaScript] js实现简单的代码运行框

<script type="text/javascript">// <![CDATA[

function runCode(obj) {
var winname = window.open('', "_blank", '');
winname.document.open('text/html', 'replace');
winname.document.write(obj.value);
winname.document.close();
}
// ]]></script>
<p>
<textarea rows="10" id="code1" style="width: 80%;">
这里是要输入的内容
</textarea><br />
<input onclick="runCode(document.getElementById('code1'))" value="运行" type="button" /></p>