null = None
Infinity = float('Infinity')
NaN = float('nan')
(But no, it's not quite Python)
It isn't. It would be None. I believe parent is mistaken.
I stand corrected; I am not that familiar with python. Though I remember reading somewhere that JSON can be evaled in both JS and Python. Perhaps the python bit is not true.
JSON looks more-or-less like a Python dict, but you still wouldn't be able to parse {"x": NaN} or {"x": Infinity}
Oddly, there's actually no language that I know of that has NaN and Infinity constants. Many languages pretty-print those float values that way, but none of the parsers can interpret them back in.
...do you mean other than JavaScript? They're not actually parser-level constants, they're just defined as globals/on the window object, but they work.