The first time I used dynamically loaded XML in the browser was in 2000, but it wasn't XMLHttpRequest -- it was in Flash.
Flash 5 came out that year, and the player was ubiquitous at something like 98% market penetration (it was preloaded by both Microsoft and Apple).
That was the first release that included real ECMAScript-compatible ActionScript, and it also had APIs for asynchronously fetching XML data. IIRC implementing it on a server was somehow tricky, but it was my first taste of a true rich client in the browser.
Flash 5 came out that year, and the player was ubiquitous at something like 98% market penetration (it was preloaded by both Microsoft and Apple).
That was the first release that included real ECMAScript-compatible ActionScript, and it also had APIs for asynchronously fetching XML data. IIRC implementing it on a server was somehow tricky, but it was my first taste of a true rich client in the browser.