// Filters elements with a data-title attribute with less than 10 characters
instance.filter(function (element) {
  return element.getAttribute('data-title').length < 10;
});

// Advanced filtering
Demo.prototype.addSearchFilter = function () {
  document.querySelector('.js-shuffle-search').addEventListener('keyup', this._handleSearchKeyup.bind(this));
};

// Filter the shuffle instance by items with a title that matches the search input.
Demo.prototype._handleSearchKeyup = function (evt) {
  var searchText = evt.target.value.toLowerCase();

  this.shuffle.filter(function (element, shuffle) {
    var titleElement = element.querySelector('.picture-item__title');
    var titleText = titleElement.textContent.toLowerCase().trim();

    return titleText.indexOf(searchText) !== -1;
  });
};