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From: Joao Rodrigues <groups_jr-1@yahoo.com.br>
Newsgroups: comp.lang.javascript
Subject: Re: Reach a digit of numerical value in array index.
Date: Sun, 22 Mar 2015 21:26:29 -0300
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Thomas 'PointedEars' Lahn wrote:
> Dr J R Stockton wrote:
>

>> Consider and test
>>
>>
>>          j = 3
>>          n = 12345 ; X = (n % Math.pow(10, j)).toString().charAt(0)
>>          n = 12045 ; Y = (n % Math.pow(10, j)).toString().charAt(0)
>>          n = 00345 ; Z = (n % Math.pow(10, j)).toString().charAt(0)
>>          Z = [X, Y, Z]        ///// ->    3, 4, 2
>
> Right, you would need to pad the toString() result if the result of the “%”
> operation would be smaller than the 1-based index (j).  I *did* test this
> approach before posting it – even though I also *did* point out *twice* that
> it is error-prone –, but not with such numbers.
>

<snip>

>
> Numeric integer literals with leading zero are parsed as octal in Mozilla
> JavaScript (and not a syntax error) when not in strict mode.  No surprise
> here.
>
>> **TESTED** in current Firefox.
>
> Confirmed in Iceweasel 31.5.0 <snip>
>

Confirmed in Chrome 41 and IE 11 as well.

   0345 // 229 [Z]
   03458 // 3458
   077 // 63
   078 // 78
   01234567 // 342391
   012345678 // 12345678
   0123456789 // 123456789

[1] <http://ecma-international.org/ecma-262/5.1/#sec-7.8.3>
     <http://ecma-international.org/ecma-262/5.1/#sec-B.1.1>

A conforming implementation, when processing strict mode code (#10.1.1), 
must not extend the syntax of NumericLiteral to include 
OctalIntegerLiteral as described in B.1.1.

In ECMAScript 6, octal number syntax uses a leading zero followed by a 
lowercase or uppercase Latin letter "O" (0o or 0O).


-- 
Joao Rodrigues