Testing doesn't indicate that for me, 55555 and 5aaa5 both fail.Ideally the "test()" method should be used though:
<html><head><script type="text/javascript">function ckField(){var errmsg = '';var OfferIDPat = /^[0-9]{1,3}[a-z]{1,2}[0-9]? \(exp: [0-9]{1,3}[a-z]{1,2}[0-9]?\)$/i; if (!OfferIDPat.test(document.OrderForm.a_Offer_ID.value)) { errmsg = errmsg + "\n" + "Zonet Rebate OfferID format #AA (ie. 5JA)"; document.OrderForm.a_Offer_ID.focus(); alert (errmsg); return false; }return true; }</script></head><body><form name="OrderForm" onsubmit="return ckField()"><input type="text" name="a_Offer_ID" size="20" /><br /><input type="submit"></form></body></html>
Try this page and let us know how it works out.You also want to make sure your javascript is enabled :)Thanks,