Slick slider tabbing

$(document).on('keydown', '.slick-initialized *', function (e) {
    var keyCode = (e.keyCode ? e.keyCode : e.which);
    if (keyCode !== 9) { return; }

    var me = $(this);

    // Traverse up to the parent slide
    var slide = me.parents('.slick-slide');
    if (slide.length < 1) { return; }

    // Get all elements in the slick slider
    var elms = slide.find('*');
    if (elms.length < 1) { return; }

    // Get tabable elements
    var tabable = [];
    elms.each(function () {
        var tabindex = $(this).attr('tabindex');
        if (tabindex === -1 || typeof tabindex === 'undefined')  { return; }

        tabable.push(this);
    });
    if (tabable.length < 1) { return; }

    // Get the current slide index and increase/decrease it's value.
    var inc = (e.shiftKey) ? -1 : 1;
    var idx = slide.data('slick-index');
        idx += inc;

    // Get a reference to the slick slider
    var slider = me.parents('.slick-initialized');

    // Loop through each tabable element
    for (var i = 0; i < tabable.length; i++) {

        // Go to next/prev slide if we're on the last/first tabable element
        if (tabable[i] === e.target) {
            if ((i === tabable.length - 1 && inc > 0) || (i === 0 && inc < 0)) {
                me[0].blur();
                e.stopImmediatePropagation();
                e.preventDefault();

                slider.slick('slickGoTo', idx);
            }
        }
    }
});