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Re: Javascript shift()

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Denis McMahon wrote:

> On Fri, 14 Jun 2013 00:15:37 -0700, JT wrote:
>> Can i somehow tell which javascript elements to shift?
>> Is something like following possible element[i].shift()
>> 
>> Many times one want to change items not necessarily at element[0], and
>> sometimes you want to swap them with another index.
>> 
>> I think the shift function should take one or two parameters or a new
>> function should be constructed.
>> 
>> element [x][y].swap();
>> 
>> It is not hard to swap elements but it make more sense then the
>> noneflexible shift() function.
> 
> If you want to swap elements x and y in an array:
> 
> element [x][y].swap();
> 
> makes no sense.

ACK.

> Your function would have to be something like:
> 
> array.swap_elements(x,y);
> 
> But why would you ever need to do this except in the context of sorting?

One can never know.

> An array is either ordered or unordered - if it's unordered it doesn't
> matter what order the elements are in,

Your logic is flawed – again.

> and if you want it ordered according to some specific algorithm, just
> write a custom sort function and sort with it:
> 
> array.sort(sortfunction);
> 
> where:
> 
> sortfunction( a, b ) {}
> 
> returns <0 if a comes first, >0 if b comes first, 0 if they're equal.

As that is a syntax error, it does not return anything.  Functions are 
declared with

  function identifier (parameter1, parameter2/*, …*/)
  {
    // …
  }

and called with

  identifier(argument1, argument2/* , … */);

[The number of arguments does not need to match the number of formal 
parameters.  If an argument is passed for which there is no parameter, its 
value is available via a numeric zero-based property of the “arguments” 
object in the function context.  If no argument is passed for a formal 
parameter, it is initialized with the “undefined” value.  Also, the value of 
the “arguments.length” property yields the number of arguments that have 
been passed to a function.]

It is not always necessary to declare a function as there are function 
expressions:

  array.sort(function (a, b) {
   // …
  });

or

  var sortNumerically = function (a, b) {
    return a - b;
  };

  array.sort(sortNumerically);

A function declaration and the latter approach has the advantage that an 
unchanging function needs only be created once.  The advantage of a function 
expression over a function declaration primarily is that its evaluation 
result (a Function instance reference) can be assigned as value to any 
property, allowing for namespacing.

[It is strongly recommended to define and use this trivial sort function, as 
the default is implementation-dependent and may sort the elements as string 
values instead.]

See also: <http://PointedEars.de/es-matrix#features>

-- 
PointedEars

Twitter: @PointedEars2
Please do not Cc: me. / Bitte keine Kopien per E-Mail.

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Thread

Javascript shift() JT <jonas.thornvall@gmail.com> - 2013-06-14 00:15 -0700
  Re: Javascript shift() Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-14 11:29 +0000
    Re: Javascript shift() Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-14 15:01 +0200
  Re: Javascript shift() Stefan Weiss <krewecherl@gmail.com> - 2013-06-14 15:03 +0200

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