Most sites did nothing like that, but they did use Javascript and would break in various ways without it. At that time, there were a lot of people admonishing web developers to test their applications with Javascript disabled. Sort of like now.
ETA: I had to look it up - XHR was first available in IE 5 as an ActiveX control. The internet at large couldn't really expect it to be available but I believe that is where we first used it.
Initial release: March 18, 1999; 18 years ago