=== again (sorry)

Maciej Stachowiak mjs at apple.com
Mon Nov 3 19:02:29 PST 2008

On Nov 3, 2008, at 6:54 PM, David-Sarah Hopwood wrote:

> Maciej Stachowiak wrote:
>> On Nov 3, 2008, at 11:34 AM, David-Sarah Hopwood wrote:
>>> Erik Arvidsson wrote:
>>>> I see a small risk with changing this. Array.prototype.indexOf is  
>>>> widely
>>>> emulated in IE and is also used a lot in browser that support it.
>>> If it is emulated, then the emulation will replace the ES3.1  
>>> version,
>>> so there can be no compatibility problem in that case.
> (This claim is not conditional on testing.)

I would expect most emulation is based on first testing for the  
presence of the method, thus it won't replace the ES3.1 version.  
That's how missing method emulation is often done in JS libraries.  
Testing (or code review) could reveal which of us is right.

>>> Overall this change will probably fix more bugs in existing code  
>>> than
>>> it introduces.
>> Have you done any testing that provides evidence for this claim?
> No, but neither has anyone arguing against the change. If I had done
> testing, I would have made a stronger claim than "probably".

I am not arguing against the change; I'm not sure anyone is, as such.  
But I think any proposed change to existing cross-browser behavior has  
to be backed up with some serious evaluation of its compatibility  
impact. Even seemingly obvious bugfixes like changing typeof null to  
not return "object" have failed to hold up under closer scrutiny.


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