Array Shuffle in JavaScript

I have yet to find a script that truly does a random shuffle across all browsers using JavaScript (no frameworks). However there are a couple of scripts I use, that are ‘good-enough’ to be used when an Array has to be shuffled. One of them which works well with a large set of records and handles good amount of iterations without hanging the browser is the Microsoft’s Shuffle alogrithm. I learnt about this algorithm from a blog post by RobWeir

The script is as follows:

<script type="text/javascript" language="javascript">
function ArrayShuffle(a) {
  var d,
  c,
  b = a.length;
   while (b) {
    c = Math.floor(Math.random() * b);
    d = a[--b];
    a[b] = a[c];
    a[c] = d
   }
   return a;
}

 var lst = [0, 1, 2, 3, 4, 5, 6, 7];
 document.write(ArrayShuffle(lst));          
</script>

The code above works well, atleast for my requirements of shuffling an array 2000 times every hour. However you need to evaluate your context and make changes in the script, if needed.

JavaScript Array Shuffle

Tip: Increase the array length (atleast 7 and above) if you want to test randomness.

Will you give this article a +1 ? Thanks in advance


About The Author

Suprotim Agarwal
Suprotim Agarwal, ASP.NET Architecture MVP (Microsoft Most Valuable Professional) works as an Architect Consultant and provides consultancy on how to design and develop Web applications.

Suprotim is also the founder and primary contributor to DevCurry, DotNetCurry and SQLServerCurry. He is the Editor of a Developer Magazine called DNC Magazine. He has also written two EBooks 51 Recipes using jQuery with ASP.NET Controls. and The Absolutely Awesome jQuery CookBook

Follow him on twitter @suprotimagarwal

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