Funkcja on('load') nie działa na mobile

$(document).ready(function(){
    $(window).on("resize", function (e) {
        checkScreenSize();
    });

    checkScreenSize();

    function checkScreenSize(){
        var newWindowWidth = $(window).width();
        if (newWindowWidth < 768) {
            var sliderImg = $("#box_slider_51 .slides li a img");

            $(sliderImg).on('load', function(){
                $("#box_slider_51 .slides").css("height", sliderImg.height());
            });

        }
        else
        {

        }
    }
});