[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=" 80%;"> 
这里是要输入的内容
</textarea><br /> 
<input onclick="runCode(document.getElementById('code1'))" value="运行" type="button" /></p>