The XMLHttpRequest API was based on the Microsoft.XMLHTTP COM library that could be used in older IE browsers starting with IE5 in 1998. Netscape (later Mozilla) added XMLHttpRequest as a native option to Gecko in 2002 and it became the norm, standardized in 2006, until fetch API became available a decade later in 2015.
Most articles that I've seen referencing the past with fetch to XMLHttpRequest tend to get muddled a bit.
https://en.wikipedia.org/wiki/XMLHttpRequesthttps://developer.mozilla.org/en-US/docs/Web/API/Fetch_API