Both IE10 Developer Preview (10.0.8102.0) and IE10 Platform Preview 4
(10.0.8103.0) output
number object
object object
We'll see if tomorrow's drop does any better.
Sounds like I should file test262 bugs as well.
From: Mark S. Miller [mailto:[email protected]]
Sent: Tuesday, February 28, 2012 14:38
To: Domenic Denicola
Cc: Allen Wirfs-Brock; Brendan Eich; [email protected]
Subject: Re: Typeof this in getters (was: eval on non-strings)
I like the output display on http://jsfiddle.net/CxdMs/16/ a bit better. I just
tried it on very recent versions of 4 or the 5 major browsers. I was shocked to
see that all of them were wrong.
Correct would be
number number
object object
Chrome 19 gave
number number
object number
Opera 12, Safari WebKit 5.1.3 (7534.53.10, r109097), and Mozilla FF Nightly 13
all gave
number object
object object
What does the latest IE10 preview do?
Domenic, as you post bugs against the browsers, please send me the URLs. Thanks.
On Tue, Feb 28, 2012 at 10:03 AM, Domenic Denicola
<[email protected]> wrote:
> Specifically regarding ToObject. It's use is important in minimizing the
> semantic differences between primitive values and Objects. In ES5 we
> eliminated the automatic wrapping of primitive values used as this values in
> method invocations. That means that in most cases 42 and (new Number(42))
> can be used interchangeably. If we start leaving out ToObject calls in random
> places the distinction between a primitive value and a wrapped primitive
> values will start tripping people up.
This actually is apropos of something I'd been meaning to ask about. Consider
the following JSFiddle:
http://jsfiddle.net/CxdMs/15/
It seems reasonably clear that the result for functions should be object
(non-strict)/number (strict), according to section 10.4.3.
But for getters, the major browsers disagree, and my spec-fu can't find
anything besides the abovementioned section. Firefox and IE9 say object/object,
while V8 says number/number. And at least one version of JavaScriptCore we have
lying around says number/object. If someone could walk me through the spec
correctly, I'd be happy to file appropriate browser bugs.
Note that this is a real-world issue. The Chai.js assertion library is trying
to break free of V8 and become useful in browsers, but is encountering problems
due to this behavior:
https://github.com/logicalparadox/chai/issues/32
Thanks all,
Domenic
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Cheers,
--MarkM
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