The API provided allows a fairly fine grained level of control over HTTP requests, allowing any request header to be set and exposes all response headers.
The original implementation came from Microsoft as an ActiveX object for IE. Mozilla followed suit and implemented XMLHttpRequest with an (almost) identical API. Konqueror (and Safari v1.2, based also on KHTML) also has an XMLHttpRequest implementation and support should be coming in Opera from v7.6x .
This resource isn’t meant as a tutorial for XMLHttpRequest but rather to gather as much information about it as possible. See the Tutorials below for getting started.