I fixed the problem I was having in class on Thursday. The
  event listener had to be declared "var submitListener =
  function() {...}" instead of either of the two techniques
  I tried in class. To be honest, I do not understand why
  the two techniques I used in class left the submitListener
  function name out of scope when init() ran ... but they
  did.

  I've put up a web page for Assignment 4 and made the due
  date this coming Tuesday. The web page has links to
  core.js and to the corrected code that I was writing in
  class on 3/27, so all you have to do is to set up the
  form and action pages and to link to the script files that
  I am providing. See the assignment web page for details.

  Have a good weekend,
  Dr. Vickery