var all = document.getElementsByTagName(“li”); var i for (i=0, max=all.length; i < max; i++) {

all[i].className = 'hidden';

} i = 0 $(document).keydown(function(e){

// left
if (e.keyCode == 37) {
  window.location.href = document.getElementById("prev").href;
}
// right
if (e.keyCode == 39) {
  window.location.href = document.getElementById("next").href;
}
// down
if (e.keyCode == 40 && i < all.length) {
  all[i].className = 'vis';
  i++;
}
// up
else if (e.keyCode == 38 && i > 0) {
  i--;
  all[i].className = 'hid';
}

});