FacetWP - generate prev/next buttons from cookie data

test.js

<div class="nav-wrapper"><!-- placeholder --></div>

<script>
(function($) {
  $(function() {
    var post_id = <?php echo $post->ID; ?>; // grab the current post ID
    var data = getCookie('fwp_posts'); // get the cookie
    if ('' != data) {
      data = JSON.parse(data);
      var pos = data.indexOf(post_id);
      if (-1 < pos) {
        if (pos > 0) { // add a "Prev" link
          var prev_id = data[pos - 1];
          $('.nav-wrapper').append('<a href="/?p=' + prev_id + '">Prev</a>');
        }
        else if (pos < (data.length - 1)) { // add a "Next" link
          var next_id = data[pos + 1];
          $('.nav-wrapper').append('<a href="/?p=' + next_id + '">Next</a>');
        }
      }
    }
  });
})(jQuery);

// http://www.w3schools.com/js/js_cookies.asp
function getCookie(cname) {
    var name = cname + "=";
    var ca = document.cookie.split(';');
    for(var i=0; i<ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1);
        if (c.indexOf(name) == 0) return c.substring(name.length,c.length);
    }
    return "";
}
</script>