This early library of JavaScript functions was written before jQuery was around. This was during the era of the so-called "browser wars," at a time when simple things like registering events had to be handled separately for legacy browsers and W3C-compliant browsers. More advanced things, like AJAX were just arriving on the scene, and each browser implemented it in its own way.
Despite the age of these functions, they are still in production, and still working with the newest browsers.
