Section VII.1. A Brief History Lesson


VII.1. A Brief History Lesson

The first implementation of the XMLHttpRequest object was available with Internet Explorer 5 for Windows, but it was only an ActiveX object (labeled Microsoft.XMLHTTP), which had to be loaded by way of IE's proprietary ActiveXObject constructor function. By the time Internet Explorer 5.5 came around, Microsoft had updated the ActiveX object and had given it a new name (Msxml2.XMLHTTP).

Meanwhile, the Mozilla engineers implemented the XMLHttpRequest object as a global object, meaning that a script can invoke the object's constructor function directly, without resorting to ActiveX. An instance of Mozilla's object had all of the properties and methods of the Microsoft version, and even added some more as time went on. Apple also saw the potential of the object for both web development and other technologies it had up its sleeve (Dashboard, for example). This activity led to Safari gaining a global XMLHttpRequest object beginning with version 1.2. Opera 8 joined the party. Finally, Microsoft implemented the object as a global object for IE 7, which allows the same code to create an instance of the XMLHttpRequest object as the other browsers.

It should be noted that "XMLHttpRequest" is such a cumbersome term, it's not uncommon to see the term abbreviated as XHR in forum discussions and articles. Because the full name already contains two acronyms (XML and HTTP), you might call XHR a "macronym."




Dynamic HTML. The Definitive Reference
Dynamic HTML: The Definitive Reference
ISBN: 0596527403
EAN: 2147483647
Year: 2004
Pages: 120
Authors: Danny Goodman

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