Array#_shuffleSelf.js

    Array.prototype._shuffleSelf = function()
    {
      var i = this.length;
      
      if(i >= 2)
      {
        var _rand = Math.random;
        
        while(--i)
        {
          var j = _rand()*i|0;
          
          var temp = this[i];
          this[i] = this[j];
          this[j] = temp;
        }
      }  
      
      return this;
    };