First, check the terms and conditions for the Webs site you're concerned about. If they allow this behavior, most modern browsers give you tools to track the AJAX calls. In this case, I used Chrome, right-clicked on the window and chose "Inspect Element" (or "alt-cmd-i"). From there, click the "Network" tab and make your search and you'll see the traffic.

When I searched for "Perl", I saw a GET request was issues to this search URL and it returned an easily parseable XML document. From there, it's up to you.