Behavior of JS unary plus operator applied on a string representing a negative hex

Question

according to MDN, when using the unary plus operator: Integers in both decimal and hexadecimal ("0x"-prefixed) formats are supported. Negative numbers are supported (though not for hex). If it cannot parse a particular value, it will evaluate to NaN. But when I run this Jasmine test (the `toBe()` matcher applies a `===` operator): ``` it("should return NaN when trying to convert a string representing a NEGATIVE HEX to the corresponding number", function() { var a = '-0xFF'; expect(typeof +a).toBe('number'); expect(isNaN(+a)).toBeTruthy(); //Fails on Chrome and Opera... }); ``` It fails on Chrome and Opera (and passes in IE, Safari and Firefox). Is it a flaw in Chrome and Opera's engines or am I missing something?

Accepted Answer

It may - or may not be seen as a flaw, depending on how one's attached to specifications. )

I've found an interesting discussion regarding this behavior. Looks like Firefox was for once in the 'better-than-spec' camp, but then fixed it according to spec.

Behavior of JS unary plus operator applied on a string representing a negative hex

Solution

Problem