Fisher-Yates

Array.prototype.shuffle.js

// http://stackoverflow.com/questions/962802/is-it-correct-to-use-javascript-array-sort-method-for-shuffling

Array.prototype.shuffle = function () {
  var tmp, current, top = this.length;
  if (top) {
    while(--top) {
      current = Math.floor(Math.random() * (top + 1));
      tmp = this[current];
      this[current] = this[top];
      this[top] = tmp;
    }
  }
  return this;
};