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From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Newsgroups: comp.lang.javascript
Subject: Re: Reach a digit of numerical value in array index.
Date: Thu, 19 Mar 2015 16:13:08 +0100
Organization: PointedEars Software (PES)
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Thomas 'PointedEars' Lahn wrote:

> […] there are (at least) three ways to retrieve the decimal
> digit from a Number value without a "temporary variable"; just error-prone
> and not very efficient ones (so kids, don’t do this at home):
> 
> a) n.toString().charAt(i)
> b) n.toString().slice(-j, -j + 1)
> c) (n % Math.pow(10, j)).toString().charAt(0)
> 
> where “n” is (a variable storing) the Number value (preferably a numeric
> integer), “i” is (a variable storing) the 0-based index of the digit
> counted from the left, and “j” is (a variable storing) the 1-based index
> of the digit counted from the right.
> 
> I do not think I need to explain why these approaches are not very
> efficient.  They are also error-prone because of limited precision of the
> IEEE 754 double-precision floating-point format as such, and of the string
> representation of its values in ECMAScript.

For recreation, here is another one:

d) Math.floor((n % Math.pow(10, j)) / Math.pow(10, j - 1))

-- 
PointedEars
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