IFrameの中に<script>を実行する

<script type="text/javascript">
    function runScript() {
        var s = document.createElement("script");
        s.type = "text/javascript";
        s.src = "http://somedomain.com/somescript";
        var iframe = document.getElementById("iframeid");

        var iframeDoc = iframe.document;
        if (iframe.contentWindow)
            iframeDoc = iframe.contentWindow.document;
        iframeDoc.body.appendChild(s)
        iframeDoc.open();
        iframeDoc.writeln(content);
        iframeDoc.close();
    }
</script>