javascript parseInt(Infinity) lolwut

gistfile1.txt

1/0
Infinity
parseInt(1/0, 5)
NaN
parseInt(1/0, 19)
18
parseInt(1/0, 20)
18
parseInt(1/0, 45)
NaN
parseInt(1/0, 22)
18

What an evil interview question to ask WTF is going on here...
Here's wtf is going on:
parseInt is coercing Infinity to the string "Infinity;
then, apparently JS will extend hex notation, so the digits of base 19 are 0123456789ABCEFGHI

parseInt parses as much as it can (1 digit, 'I') whose value is 18.
Here by passing some different strings, the behavior becomes clear:

parseInt("H", 19)
17
parseInt("G", 19)
16

(In a way you are asking for it: what else is the function supposed to do when asked to parse integers of a base greater than 16?
Well, probably it should error out...)

"Evil" is correct!