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Groups > comp.lang.javascript > #22359

Re: Date Conversion ?

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On 17/12/2013 12:12, Thomas 'PointedEars' Lahn wrote:

>> // low and high are now the minimum and maximum values from the array
>
> In implementations of ECMAScript Ed. 3, it is easier and probably more
> efficient to use the built-in Math.min() and Math.max() methods:
>
>    var low = Math.min.apply(Math, arr);
>    var high = Math.max.apply(Math, arr);

Brilliant!

> They also work for Date instances as Array elements because they convert the
> arguments to Number before comparison.  In general, if these methods are
> implemented, it is easiest to overwrite the “valueOf” property of the
> prototype object of the objects for the call – or provide the objects
> themselves with one –, which is triggered first by the internal ToNumber
> algorithm when called with hint Number.
>
> <http://ecma-international.org/ecma-262/5.1/#sec-15.8.2.11>
> <http://ecma-international.org/ecma-262/5.1/#sec-9.3>
> <http://ecma-international.org/ecma-262/5.1/#sec-9.1>
> <http://ecma-international.org/ecma-262/5.1/#sec-8.12.8>
> <http://ecma-international.org/ecma-262/5.1/#sec-15.9.5.8>
>
> One can also access the first and last element of a sorted array:
>
>    var sortedCopy = arr.slice().sort(function (a, b) { return a - b; });
>    var low = sortedCopy[0];
>    var high = sortedCopy[sortedCopy.length - 1];
>
> <http://ecma-international.org/ecma-262/5.1/#sec-15.4.4.11>

or

var low = sortedCopy.shift();
var high = sortedCopy.pop();

>
> Finally, all implementations of ECMAScript Ed. 5 – not just JavaScript
> anymore – provide Array.prototype.reduce(), as mentioned by Björn:
>
>    var low = arr.reduce(
>      function (accumulator, e, i, a) {
>        if (е < accumulator)
>        {
>          return e;
>        }
>
>        return accumulator;
>      },
>      arr[0]);
>
> <http://ecma-international.org/ecma-262/5.1/#sec-15.4.4.21>

'accumulator' is a bad name, as you are not accumulating anything in 
that function.

>
> There appears to be no point to use .map() here because if you have .map()
> you have .reduce() and can thereby shorten the scope chain.
>

ACK.


-- 
Joao Rodrigues (J.R.)

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Thread

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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