Gets random image from image set

markup.php

<div class="randomImageSet hidden">
    <?php if (function_exists('dynamic_sidebar') && dynamic_sidebar('contact_page_banner_widget')) : else : ?><?php endif; ?>
</div>

<div id="randomImage" class="relative top-bk"></div>

randomImg.js

const imgArray = [];
    (function slidesArray() {

        $(".randomImageSet img").each(function() {

            var arrayItem = { image: $(this).attr('src')};

            imgArray.push(arrayItem);

        });

        return imgArray;
    }());

    var randomArray = imgArray;

    (function choosePic() {
        var randomNum = Math.floor(Math.random() * randomArray.length);
        var img = randomArray[randomNum].image;
        var random = document.getElementById("randomImage");
        random.style.backgroundImage = 'url(' + img + ')';
    }());