Did you do a Khan Academy course on JS even though you already know it, Piers?
That makes me realize how much about JS I don’t really own. Which makes it relatively opaque.
Prototype hammering is a form of monkey patching and is IMO highly opaque.
I have written a lot of plain old C. I found the language very clear, such that I very rarely didn’t understand the code. But the programs it creates are another story.
With very high level languages like BASIC, the DWIM philosophy leads to baffling debugging because the compiler is deliberately inconsistent.