Frame内页面里的FORM对象附值问题,大家帮忙看看

b.jsp<html>
<body>
<form name=form123 method=post action="c.jsp">
<input type=hidden name="openerurl" value="">
</form></body>
</html>
<script language="javascript">
var openurl = parent.document.location.toString();
document.form123.openerurl.value=openurl;            
alert(document.form123.openerurl.value);               
document.form123.submit();
</script>