Shuffles a given array using an implemented version of Fisher–Yates algorithm

shuffle.js

function shuffle(array) {
  var counter = array.length, temp, index;
  
  // While there are elements in the array
  while (counter--) {
      // Pick a random index
      index = (Math.random() * (counter+1)) | 0;
  
      // And swap the last element with it
      temp = array[counter];
      array[counter] = array[index];
      array[index] = temp;
  }
  
return array;
}

Fisher–Yates shuffle reference