Jquery - iterate focus with keyboard arrows on images in different div’s

hi all,
i want to be able to focus images that has the same class (in a thumbnail scroller).
this is what i have:

<div class="swiper-wrapper" id="swiper-wrapper" >          
                             <div class="swiper-slide" tabindex="0"><img src="cards/jpeg1.jpg" alt="" class="thumb"></div>

                             <div class="swiper-slide" tabindex="-1"><img src="cards/jpeg2.jpg" alt="" class="thumb"></div>



                   var parent = document.getElementById("swiper-wrapper");
                    var children = document.getElementById("swiper-wrapper").children;

                    for (var i = 0; i < children.length; i++) {
                        $('.swiper-slide, select').keydown(function (e) {
                            if (e.keyCode == 39) {
                                $(this).next('.swiper-slide , select').focus();
                            else if (e.keyCode == 37) {
                                $(this).prev('.swiper-slide , select').focus();

this gives me keyboard control focus only on the div’s containing the images.
how do i improve it to move the focus between the actual images?