To clarify, the expected results here are: Non-strict Typeof this inside a function when called on a number: object Typeof this inside an Object.prototype getter when used on a number: object Strict Typeof this inside a function when called on a number: number Typeof this inside an Object.prototype getter when used on a number: number right?
There's over a hundred test cases that have already been created, and will be contributed 'soon' to cover https://bugs.ecmascript.org/show_bug.cgi?id=180. One such test case is: function foo() { 'use strict'; return typeof(this); } function bar() { return typeof(this); } return foo.call(1) === 'number' && bar.call(1) === 'object'; Another that seem relevant here is: function testcase() { var o = {}; Object.defineProperty(o, "foo", { get: function() { "use strict"; return this; } }); return o.foo===o; } On that note, is there anything that's particularly interesting spec-wise in defining foo on Object.prototype instead of a generic object and validating there? Thanks! Dave From: es-discuss-boun...@mozilla.org [mailto:es-discuss-boun...@mozilla.org] On Behalf Of Mark S. Miller Sent: Tuesday, February 28, 2012 3:45 PM To: Domenic Denicola Cc: es-discuss@mozilla.org; Brendan Eich Subject: Re: Typeof this in getters (was: eval on non-strings) On Tue, Feb 28, 2012 at 3:38 PM, Domenic Denicola <dome...@domenicdenicola.com<mailto:dome...@domenicdenicola.com>> wrote: 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. Oops. I meant for Yes, thanks! to be placed here. Yes, thanks for filing test262 bugs as well. From: Mark S. Miller [mailto:erig...@google.com<mailto:erig...@google.com>] Sent: Tuesday, February 28, 2012 14:38 To: Domenic Denicola Cc: Allen Wirfs-Brock; Brendan Eich; es-discuss@mozilla.org<mailto:es-discuss@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 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 <dome...@domenicdenicola.com<mailto:dome...@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: 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 _______________________________________________ es-discuss mailing list es-discuss@mozilla.org<mailto:es-discuss@mozilla.org> https://mail.mozilla.org/listinfo/es-discuss -- Cheers, --MarkM -- Cheers, --MarkM
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