A few years before I encountered jQuery, I found an experimental programming language that tried to do away with the distinction between variables that contained 0-1 values and those that contain 0-n. In this language, all operations were set operations. When your data model changed from 1:1 to 1:n (classic example - user:address is probably the concept I’ve seen mis-modeled the most often).

So when I saw jQuery for the first time, I’d already been primed for this concept. I’m a little surprised it’s been used so infrequently.