[Zope] javascript experts?

I am using some dynamic javascript to build form input controls and I have got everything working perfectly in all browsers except IE. The javascript uses square bracket notation to allow the phones.number:records to build multiple database input records for Zope. if (eval("document.forms.playlist['phones.number:records'][" + idx + "].value") > 0) However,IE interprets it as: "document.forms.playlist.phones.number:records" and of course therefore does not find the element referenced. Can anyone suggest a workaround for IE in this respect. Thanks Garry