Object Detection
http://developer.apple.com/internet/webcontent/objectdetection.html

Apple Inc.
2006

Abstract:

The pace of new browser releases may be slower than it was in the early days, but developers must still confront a bemusing array of browser versions and brands that support some JavaScript features but not others. To combat the problem, scripters commonly provide two or more code branches so that a browser follows an execution path containing statements that it supports. Browser sniffing — the task of inspecting navigator object properties for version information — has become largely unmanageable given the browser version permutations available today. This article presents details on an alternative solution — object detection — that frees JavaScript developers from most of this versioning mess.