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Groups > comp.lang.javascript > #23516
| From | Joao Rodrigues <groups_jr-1@yahoo.com.br> |
|---|---|
| Newsgroups | comp.lang.javascript |
| Subject | Re: arr.push(obj); |
| Date | 2014-03-11 06:59 -0300 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <lfmmq3$895$1@speranza.aioe.org> (permalink) |
| References | <b766bb8c-c9a9-4914-bf16-fe342ef06930@googlegroups.com> <94a86543-50f2-4232-b988-c12db82404cb@googlegroups.com> <73df0840-d0e7-46c9-98c5-126d7f7562ad@googlegroups.com> <eb1fc2f6-1f49-4d8c-a71a-c0c7056fcb85@googlegroups.com> |
On 11/03/2014 01:19, jonas.thornvall@gmail.com wrote:
> Den tisdagen den 11:e mars 2014 kl. 04:28:25 UTC+1 skrev jonas.t...@gmail.com:
>> Den tisdagen den 11:e mars 2014 kl. 04:19:49 UTC+1 skrev jonas.t...@gmail.com:
>>
>>> Den tisdagen den 11:e mars 2014 kl. 01:38:12 UTC+1 skrev jonas.t...@gmail.com:
<snip>
>> I did find a page that told that arr[-1] get the last element of array, so it seem negative indexes not allowed.
That is a misconception.
>
> I was wrong it is allowed or at least working.
>
> <script type="text/javascript">
> var arr=[];
> for (i=10;i>=-20;i--) {arr[i]=i;}
> arr[-22]=-22;
> for (i=10;i>=-22;i--) {document.write(arr[i],",");}
> </script>
According to the section 15.4 of the ECMAScript 5.1 Specification, "A
property name P (in the form of a String value) is an array index if and
only if ToString(ToUint32(P)) is equal to P and ToUint32(P) is not equal
to 232−1". So, I think this is why you can set negative indices to an
array. But the array's length property value is always a nonnegative
integer less than 232.
Thereby, your code creates a mutilated array, and some of the native
array methods might not work as expected. For instance, arr.length will
return 11, and arr.join(',') will yield 0,1,2,3,4,5,6,7,8,9,10
--
Joao Rodrigues
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arr.push(obj); jonas.thornvall@gmail.com - 2014-03-10 17:38 -0700
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-10 20:19 -0700
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-10 20:28 -0700
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-10 21:19 -0700
Re: arr.push(obj); Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2014-03-11 06:59 -0300
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-11 16:02 +0100
Re: arr.push(obj); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-11 16:22 +0000
Re: arr.push(obj); Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2014-03-11 13:32 -0300
Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-11 10:21 +0100
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 03:53 -0700
Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-11 14:03 +0100
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 07:45 -0700
Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-11 16:24 +0100
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 10:40 -0700
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 10:51 -0700
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-11 19:23 +0100
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 15:33 -0700
Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-12 00:37 +0100
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 16:46 -0700
Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-12 01:05 +0100
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 01:40 +0100
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 00:48 +0100
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 15:43 -0700
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 16:18 -0700
Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-12 00:39 +0100
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 00:52 +0100
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 00:49 +0100
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 17:16 -0700
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 02:07 +0100
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 18:13 -0700
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-13 02:25 +0100
Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-13 11:03 +0100
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-12 07:46 -0700
Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-12 01:27 +0100
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 01:44 +0100
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-11 16:26 +0100
Re: arr.push(obj); Carlos Pedro <carlospedr@gmail.com> - 2014-03-11 09:21 -0700
Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-11 18:01 +0100
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-11 19:15 +0100
Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-11 20:32 +0100
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 01:01 +0100
Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-12 04:08 +0100
Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 18:00 +0100
Re: arr.push(obj); Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2014-03-11 06:24 -0300
Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 03:47 -0700
Re: arr.push(obj); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-11 15:19 +0000
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