First, here is the PHP book I am recommending:

    PHP Solutions: Dynamic Web Design Made Easy
    David Powers
    Friends of Ed, 2006
    ISBN 978-1-5909-731-6

  I am recommending it rather than requiring it because you may be comfortable
  learning PHP some other way, such as by using the online documentation at
  http://php.net -- which is very good and includes sample code throughout.

  Also, we will be working with a PostgreSQL database, and the Powers book uses
  MySQL. The differences are relatively minor, but you won't be able to use the
  examples from the book exactly as they are presented.

  Second, I updated my form_handler.js after class today; you can see the
  updated version on the Assignment_4_Solution.xhtml web page. I've written a
  guide to the new version below.

  So, please submit Assignment 4 immediately if you have not already done so.
  (The keyup listener covered today is not required.)

  And have a great Spring break!

  Dr. Vickery

  Notes On My Assignment 4 Solution

    The sample solution I have provided shows how to set up event listeners for
    keyup, change, and submit events using an anonymous self-executing function
    to provide a private "namespace" for the application to work in. I think
    that part is pretty clear, but let me know if not.

    The other thing my solution does is to use some well-established JavaScript
    techniques to reduce the size of the code a lot compared to how you might
    write equivalent code in an object oriented language like Java or a
    procedural language like C or C++. In particular, my solution dynamically
    alters DOM tree node objects to so that they carry three additional pieces
    of informtion around with them.

      1. There is an element that has an error message associated with the two
      input elements for this assignment, and a reference to that element is
      added to the input element objects; I used the name 'msg' for the variable
      that holds this reference. It is initialized during init() and used
      during validateElement(), which changes the class values of this element
      to control its visibilty.

      2. There is a boolean variable named isValid associated with the two input
      elements, kept in the same DOM tree objects as #1 above. Until
      validateElement() has been called for an element, this variable is
      undefined. Simply assigning a value to it creates it if it does not
      already exist.

      3. There is a regular expression for each input element that is used to
      test whether an element's value is valid or not. Adding these regular
      expressions to the input elements' DOM objects as the variable named regex
      is the big change in today's version of the code. The regex variables are
      initialized in init() and used in validateElement() to perform the
      validation. Handling the regular expressions this way eliminated the two
      separate functions for handling changes to the two different input
      elements; now change events for both elements go to the same function,
      (changeListener()), which simply passes 'this' on to validateElement().

    There are also changes in today's code, compared to the previous version, to
    deal with keyup events.

    I think studying today's version of the sample code will be helpful even
    though you (should) have already studied the previous version.

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