Created by Microsoft and adopted soon thereafter by Mozilla, the XMLHttpRequest object is
today fully supported by the majority of Web browsers. As you’ll see in a moment, the implementation
can significantly differ from one browser to the next, even though the top-level interface
is nearly identical. For this reason, a W3C committee is at work with the goal of precisely
documenting a minimum set of interoperable features based on existing implementations.
Note : The XMLHttpRequest object originally shipped as a separate component with Internet
Explorer 5.0 back in the spring of 1999. It is a native component of all Microsoft operating
systems that have shipped since. In particular, you’ll certainly find it installed on all machines
that run Windows 2000, Windows XP, and newer operating systems.
