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Re: JS Array problem

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Mel Smith wrote:

> "danca" <cyberdanny@tiscalinet.it> wrote […]:
>> Il 20/10/2014 23:11, Mel Smith ha scritto:
>> Maybe something like this?
>>
>> var a,b,c,d ;
>> var abcd = ["a","b","c","d"] ;
>> for (var i= 0; i<abcd.length; i++) {
>>      eval(abcd[i]+"="+i);
>> }
> 
> […]
>     Yes, That's what I was looking for.

Hardly, as it is harder to debug and more error-prone.  It will not work in 
strict mode (the scope chain of eval code is empty then), which you should 
be using in order to avoid common programming errors.

Also,

  for (var i = 0, len = abcd.length; i < len; ++i)

is more efficient when “abcd.length” does not change;

  for (var i = abcd.length; i--;)

is even more efficient if the array is not sparse and order does not matter.  

If the array-like object is sparse, the most efficient way, where order 
matters and non-index own properties are not expected, is probably

  var indexes = Object.keys(abcd);
  for (var i = 0, len = indexes.length; i < len; ++i)
  {
    var index = indexes[i];
    abcd[index] = …;
  }

(Array indexes are names of own enumerable properties.  If non-index own 
properties are expected, an additional test of the property name is 
required.)

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JS Array problem "Mel Smith" <syntel@cox.net> - 2014-10-20 15:11 -0600
  Re: JS Array problem Denis McMahon <denismfmcmahon@gmail.com> - 2014-10-20 22:25 +0000
    Re: JS Array problem "Mel Smith" <syntel@cox.net> - 2014-10-21 08:33 -0600
  Re: JS Array problem danca <cyberdanny@tiscalinet.it> - 2014-10-21 09:08 +0200
    Re: JS Array problem Une Bévue <unbewusst.sein@fai.invalid> - 2014-10-21 09:42 +0200
      Re: JS Array problem "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-10-21 09:47 +0200
        Re: JS Array problem Une Bévue <unbewusst.sein@fai.invalid> - 2014-10-21 09:51 +0200
          Re: JS Array problem "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-10-21 09:53 +0200
        Re: JS Array problem Une Bévue <unbewusst.sein@fai.invalid> - 2014-10-21 09:52 +0200
          Re: JS Array problem "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-10-21 10:36 +0200
      Re: JS Array problem "Mel Smith" <syntel@cox.net> - 2014-10-21 08:36 -0600
    Re: JS Array problem "Mel Smith" <syntel@cox.net> - 2014-10-21 08:35 -0600
      Re: JS Array problem Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-10-21 19:02 +0200
  Re: JS Array problem "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-10-21 13:12 +0200
    Re: JS Array problem "Mel Smith" <syntel@cox.net> - 2014-10-21 08:38 -0600
  Re: JS Array problem "Mel Smith" <syntel@cox.net> - 2014-10-21 08:29 -0600
    My 'actual' code "Mel Smith" <syntel@cox.net> - 2014-10-21 11:20 -0600
      Re: My 'actual' code Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-10-21 19:52 +0100
        Re: My 'actual' code Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-10-21 21:23 +0200
  Re: JS Array problem Violet Deng <dengviolet@gmail.com> - 2014-10-28 02:03 -0700
    Re: JS Array problem "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-10-28 10:08 +0100

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