Most math books/papers come complete with definitions(incredibly helpful), theorems and proofs. In other words they are "well-documented" in programmer talk. Books on programming language semantics/syntax and general physics haven't reached the level of anal-ness that math texts exhibit when it comes to details, definitions and consequences. So, I'd say whichever comes with more hand-wavy (non)arguments is more difficult to pick up unless you're up for straight up memorization.
There's only 5 possible cases that determine the value of the "this" keyword, so I'd say that frisbee physics are harder.