Typeof this in getters (was: eval on non-strings)
domenic at domenicdenicola.com
Tue Feb 28 15:38:31 PST 2012
Both IE10 Developer Preview (10.0.8102.0) and IE10 Platform Preview 4 (10.0.8103.0) output
We'll see if tomorrow's drop does any better.
Sounds like I should file test262 bugs as well.
From: Mark S. Miller [mailto:erights at google.com]
Sent: Tuesday, February 28, 2012 14:38
To: Domenic Denicola
Cc: Allen Wirfs-Brock; Brendan Eich; es-discuss at mozilla.org
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
Chrome 19 gave
Opera 12, Safari WebKit 5.1.3 (7534.53.10, r109097), and Mozilla FF Nightly 13 all gave
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 <domenic at domenicdenicola.com> 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:
It seems reasonably clear that the result for functions should be object (non-strict)/number (strict), according to section 10.4.3.
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:
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