Return text from a select field

hi, i have a select field (aka dropdown box), i know how to retrieve the value (index value). Thats straight forward, but now i want the text value that is displayed to the user. in java script, i would do it like this:

var e = document.getElementById(“InterestRate”);
var strUser = e.options[e.selectedIndex].text;

“InterestRate” is the name of the select field

how do i do this inside scriptcase in the ajax events?