140byt.es -- Array Shuffle

README.md

Shuffle an array in-place using Fisher–Yates shuffle

var shuffle = function(a,b,c){for(b=a.length;b;c=0|b*Math.random(),a[c]=[a[--b],a[b]=a[c]][0]);}

var a = [1, 2, 3, 4, 5, 6, 7];

shuffle(a); console.log(a);
// [2, 3, 6, 7, 4, 1, 5]

shuffle(a); console.log(a);
// [3, 6, 5, 2, 1, 4, 7]

annotated.js

function // Shuffle
  (a,    // Array

// Local variables:
   i,    // Element iterator
   j)    // Element to swap
{

  for (
    i = a.length;          // Start at the end
    i;                     // Iterate over the whole array except the first element

    j = 0 |                // Pick (Math.floor)
        i * Math.random(), // A random position before the current element

                           // --i
                           // Swap a[i] and a[j]
    a[j] = [a[--i], a[i] = a[j]] [0]
  );

}

index.js

function(a,b,c){for(b=a.length;b;c=0|b*Math.random(),a[c]=[a[--b],a[b]=a[c]][0]);}

LICENSE.txt

Copyright (c) 2011 Christopher Chedeau, http://blog.vjeux.com/
 
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
 
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

package.json

{
  "name": "array_shuffle",

  "description": "Shuffle an Array",

  "keywords": [
    "140bytes",
    "shuffle",
    "array" 
  ]
}

I played around with pseudorandom numbers and it works but is longer than simply calling Math.random(). And it's not self contained, it needs to be called with an initial value for the generator, e.g. shuffle(a, new Date().getTime()). Without, it will create the same result every time.

function(a,b){a.sort(function(){return.5-(b=b*7%99)%2})}

In the end I came up with a solution worth 108 Euro. No, not really. It's clearly a fake but it kind of shuffles all types of arrays. For example, the array [1,2,3,4,5,6,7,8,9,10] becomes [2,7,8,3,9,6,4,10,1,5]. Looks random but isn't. It's the same every time. The function also accepts an initial value but since it's boolean there are only two possibilities how a specific array is ordered.

function(a,b){a.sort(function(){return b=!b})}