Trigger GalleryCSS changes via JavaScript, eg from swipe events on touch devices. Requires GalleryCSS (obviously) - https://github.com/benschwarz/gallery-css.

GalleryCss.js

/**
 * GalleryCss JS
 * Trigger GalleryCSS changes via JavaScript, eg from swipe events on touch devices.
 * Requires GalleryCSS (obviously) - https://github.com/benschwarz/gallery-css
 *
 * GalleryCss.next(); // move to the next item, or loop back to the start
 * GalleryCss.prev(); // move to the previous item, or loop back to the end
 * GalleryCss.goTo(); // jump to a specific item (zero-based index)
 *
 */

var GalleryCss = {
  _base: '.controls a',
  _first: ':first-child',
  _last: ':last-child',

  _current: function() {
    var target   = window.location.hash,
        selector = target === '' ? this._first : '[href="' + target + '"]',
        current  = document.querySelector(this._base + selector);

    // if the URL Hash was not from Gallery CSS, fall back to the first link.
    if (!current) current = document.querySelector(this._base + this._first);
    return current;
  },
  _next: function() {
    var current = this._current(),
        next = current.nextElementSibling || document.querySelector(this._base + this._first);
    return next;
  },
  _prev: function() {
    var current = this._current(),
        prev    = current.previousElementSibling || document.querySelector(this._base + this._last);
    return prev;
  },
  _at: function(idx) {
    var list = document.querySelectorAll( this._base ),
        item = list.item(idx);
    return item;
  },
  _switchTo: function(item) {
    var el, href;

    switch(item) {
      case 'next':
        el = this._next();
        break;
      case 'prev':
        el = this._prev();
        break;
      default:
        item = parseInt(item, 10);
        el = this._at(item);
    }

    if ( el ) {
      window.location.hash = el.getAttribute('href');
    }
  },

  // Public
  next: function() {
    this._switchTo('next');
  },
  prev: function() {
    this._switchTo('prev');
  },
  goTo: function(idx) {
    this._switchTo(idx);
  }
};