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Re: Date Conversion ?

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On 20/12/2013 19:29, Thomas 'PointedEars' Lahn wrote:
> Thomas 'PointedEars' Lahn wrote:
>
>> Bjoern Hoehrmann wrote:

<snip>

>> you can do much the same as in Perl:
>>
>>    […]
>>      /*
>>       * or
>>
>>           var m = ({
>>             "Jan": 1,
>>             "Feb": 2,
>>             …
>>           })[matches.groups["m"]];
>>
>>       * with JSX:regexp.js [2]
>>       */
>>      var m = ({
>>        "Jan": 1,
>>        "Feb": 2,
>>        …
>>      })[matches[0]];
>
>      var m = {
>        "Jan": 1,
>        "Feb": 2,
>        …
>      }[matches[0]];
>
> (and similar; without parentheses) suffices because the right-hand side of
> the assignment is evaluated in Expression context, not Statement context.
>
> This is different with
>
>    var s = '{"foo": "bar"}';
>
>    /* Syntax error in the /Program/ parsed by eval() */
>    var o = eval(s):
>
>    /* Correct syntax in the /Program/ parsed by eval() */
>    var o = eval("(" + s + ")"):
>
> – as an insecure but backwards-compatible stand-in for JSON.parse() – and
> when for some reason you want to access a specific object referred by
> another object's property, based on a name:
>
>    var s = "foo";
>
>    {
>      "foo": ["baz", "bar"]
>    }[s].sort();
>
> is a Syntax error;
>
>    var s = "foo";
>
>    ({
>      "foo": ["baz", "bar"]
>    })[s].sort();
>
> is not.

It is so because an Expression cannot start with "function " or "{"
<http://ecma-international.org/ecma-262/5.1/#sec-12.4>

Besides the surrounding parentheses, we can use the comma operator:
<http://ecma-international.org/ecma-262/5.1/#sec-11.14>

var s = '{"foo": "bar"}';
var o = eval("1," + s);

Or:

var s = "foo";
1, {
      "foo": ["baz", "bar"]
    }[s].sort();

-- 
Joao Rodrigues (J.R.)

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Date Conversion ? "Mel Smith" <med_cutout_syntel@aol.com> - 2013-12-16 15:55 -0700
  Re: Date Conversion ? Bjoern Hoehrmann <bjoern@hoehrmann.de> - 2013-12-17 01:06 +0100
    Re: Date Conversion ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-12-19 12:34 +0100
      Re: Date Conversion ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-12-20 22:29 +0100
        Re: Date Conversion ? Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2013-12-23 10:00 -0200
  Re: Date Conversion ? JJ <duh@nah.meh> - 2013-12-17 07:06 +0700
    Re: Date Conversion ? Denis McMahon <denismfmcmahon@gmail.com> - 2013-12-17 00:35 +0000
      Re: Date Conversion ? "Mel Smith" <med_cutout_syntel@aol.com> - 2013-12-16 18:16 -0700
      Re: Date Conversion ? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2013-12-17 10:09 +0100
        Re: Date Conversion ? Denis McMahon <denismfmcmahon@gmail.com> - 2013-12-17 17:02 +0000
        Re: Date Conversion ? Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-12-18 19:14 +0000
          Re: Date Conversion ? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2013-12-19 15:42 +0100
            Re: Date Conversion ? "Michael F. Stemper" <michael.stemper@gmail.com> - 2013-12-19 09:20 -0600
              Re: Date Conversion ? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2013-12-20 10:04 +0100
      Re: Date Conversion ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-12-17 15:12 +0100
        Re: Date Conversion ? Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2013-12-17 18:10 -0200
          Re: Date Conversion ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-12-17 21:42 +0100
    Re: Date Conversion ? Bjoern Hoehrmann <bjoern@hoehrmann.de> - 2013-12-18 13:36 +0100
  Re: Date Conversion ? Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-12-17 19:02 +0000
    Re: Date Conversion ? "Mel Smith" <med_cutout_syntel@aol.com> - 2013-12-17 20:51 -0700
      Re: Date Conversion ? Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-12-19 20:21 +0000
        Re: Date Conversion ? "Mel Smith" <med_cutout_syntel@aol.com> - 2013-12-20 09:52 -0700
          Re: Date Conversion ? Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-12-21 20:41 +0000
            Re: Date Conversion ? "Mel Smith" <med_cutout_syntel@aol.com> - 2013-12-22 09:52 -0700

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