In order to demonstrate how to integrate Ajax into your WordPress plugins, we've chosen a textbook example: automatically showing search results. Later in this book, we'll use Ajax to do more complicated things, but first we're going to cover the basics by breathing life into the standard search widget.
If you don't have the search widget enabled on your site, enable it now so you can see what we're talking about. In the WordPress manager, click on the Appearance | Widgets link and then drag the Search widget into the Primary Widget Area so that it becomes active. On a tangential note, WordPress uses Ajax to save your widget selections without you having to click anything.
Take a look at your home page to verify that you see the search widget. Try searching for a few terms to get a feel for how this process works.
Pretty basic, eh? You've seen this type of thing before, but let's take a moment to talk about what is really going on here. On a technical level, here is what...