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Message-ID: <1740728.os95qiCnSi@PointedEars.de>
From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Reply-To: Thomas 'PointedEars' Lahn <cljs@PointedEars.de>
Organization: PointedEars Software (PES)
Date: Fri, 27 Jan 2012 11:41:56 +0100
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Subject: Re: Comparing arraies
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.javascript:10637

Denis McMahon wrote:

> Gene Wirchenko wrote:
>> Denis McMahon wrote:
>>> […]
>>> function are_identical(var1, var2) {
>>> return JSON.stringify(var1) === JSON.stringify(var2); }
>>>
>>> I think this would work for anything that can be stringified by the
>>> JSON.stringify() method.
>> 
>>      Why not just toString()?
>>           if (var1.toString()===var2.toString())
> 
> var x;
> x.fred = 9;
> x.jim = 23.654;
> x.sue[0] = [15,"mouse",[12,14,5,"BASHER"],543.876];
> x.sue[1] = "is x.toString() defined?";

This code cannot run (as-is; if `x' was assigned a reference to an object 
with a `sue' property before, then it *could* work), and does not constitute 
a proof at all.

A useful example showing why toString() does not suffice for all cases is

  /* "1,2,3,4"                 == "1,2,3,4"                 */
     [1, [2, 3], 4].toString() == [[1, 2], [3, 4]].toString()

If the JSON property is unavailable or wrong implemented, it can be 
emulated, either by using the implementation from <http://json.org/> or 
another object serializer.


PointedEars
-- 
Anyone who slaps a 'this page is best viewed with Browser X' label on
a Web page appears to be yearning for the bad old days, before the Web,
when you had very little chance of reading a document written on another
computer, another word processor, or another network. -- Tim Berners-Lee