ListShuffler.js

var ListShuffler = function(targetExpr, itemExpr) {
  this.targetExpr = targetExpr || '';
  this.itemExpr = itemExpr || 'li';
  this.targetEl = {};
  this.items = [];
  this.init();
  this.do();
}

ListShuffler.prototype.init = function() {
  this.targetEl = document.querySelector(this.targetExpr);
  var items = this.targetEl.querySelectorAll(this.itemExpr);
  for (var i = items.length - 1; i >= 0; i--) {
    this.items.push(items[i]);
  };
  return this;
};

ListShuffler.prototype.shuffle = function() {
  var array = this.items;
  for (var i = array.length - 1; i > 0; i--) {
    var j = Math.floor(Math.random() * (i + 1));
    var temp = array[i];
    array[i] = array[j];
    array[j] = temp;
  }
  this.items = array;
};

ListShuffler.prototype.clear_ = function() {
  var el = this.targetEl;
  while (el.firstChild) {
    el.removeChild(el.firstChild);
  }
};

ListShuffler.prototype.put = function() {
  for (var i = this.items.length - 1; i >= 0; i--) {
    this.targetEl.appendChild(this.items[i])
  };
};

ListShuffler.prototype.do = function() {
  this.shuffle();
  this.clear_();
  this.put();
};