and typeof NaN == "number" is also part of the standard, it is valid to pass NaN to functions that accept numbers, and it's expected to propagate or change back to normal numbers (e.g. NaN^0=1)

If anything, JS has plenty of problems due to its too literal interpretation of NaN.

I mean, it is a weird statement in that the language apparently needs a === operator.

Of course, after looking up what === is, the behavior is obvious.

That wouldn't change anything here. This behavior is due to the IEEE 754 number spec, which is implemented in many languages.

The floating point behavior is the obvious part, the === operator is the head-scratcher.

Yeah, this is a IEEE754 floating point issue.

I'm not sure why it seems there hasn't been any progress made on making floating point types less error-prone in the last few decades.

Rounding errors are unavoidable when representing an infinite amout of numbers in a fixed number of bits. But in many cases a decimal type (like in C#) would have more intuitive behvior than binary floating point. A decimal type have been proposed for JavaScript but I dont know how far along it is.