For this new project we decided to work with the YUI (Yahoo User Interface) Javascript library. For the widgets provided, the YUI makes javascript development extremely fast and bug free. The documentation was extremly clear and contained plenty of examples.
We used the Connection Manager to make the XMLHttpRequest calls. It provides a simple interface for managing this process. Callback functions for success or failure are simple to work with. We returned most of the calls in JSON format. JSON was easy to return from Perl using the JSON module.
We also used the autocomplete widget to provide an address lookup while the user is typing. This came out very nicely but we will probably have to modify it in the future. One property we looked for but did not find is a way to stop querying the data source on the server when the server has no more completions.
W also used the Container widget to provide popups. The popups are very simple and extremely polished. We used the ‘modal’ property to require the user to respond and then close the popup before continuing.
We also played a bit with the tabview, although we have no public demonstrations of this control. For the rest you can see http://estimatepropertyvalues.com