This is exactly the same as Test 2 except that the JavaScript has been rewritten to use the Prototype library which, besides many much deeper benefits, makes the code so much simpler and more manageable. It also, very importantly, uses a different, DOM-based approach to setting up handlers when the page loads.
As before, the form can be submitted only if there's something (in this case, anything at all) in both user name and password fields.
Try submitting the form in various ways. If the cursor is in the User name field and you hit the Enter key, or if you click the Go button, everything behaves normally. If you clicked in the Password field on the way - maybe you typed something into it - you might have noticed the Typinator icon change, but it would change back when you clicked on either the User name field or the Go button. What happens, however, if you submit the form by hitting Enter when the cursor is in the Password field? Try it and see...