<script language="javascript">
if (!Check('cn',1))
{
                alert("请正确键入URL!");
                document.createurl.URL.focus();
                return false;
            }
else alert('OK');

function Check(str,diff)
{
switch (diff)
{
case 1:
var part = /.*\w+\.{1}\w+.*/;
}
if (part.test(str)) return true;
else return false;
}
</script>