backbone? magic? backbone is 1534 lines of straightforward, well written, well documented javascript. backbone is about as simple and un-magic as MVC gets, by design.
This is one of the lines in backbone.js:
if ((callback && callback !== (ev.callback._callback || ev.callback)) || (context && context !== ev.context))
I feel stuff like this takes a lot of mental power to understand the context that it is being executed in and what exactly it is doing. It feels like I am knee deep in some obfuscated C code.
It definitely gets the job done; however, I would imagine someone figures they'll come back and refactor at some point. Code is never finished, it is merely shipped. This is shipping code, but it certainly can be refactored into a more intention revealing function.
It's a trade-off. If you pull it into a new function, it adds LOC. It also is another layer of abstraction. Is it worth it? Perhaps...but maybe not. Just looking at this one line of code in isolation without context is a bit unfair though.