setInterval(function () {
    document.querySelectorAll('div.img-title').forEach(function (title) {
        title.parentNode.removeChild(title);
    });

    document.querySelectorAll('img.img').forEach(function (img) {
        if (!img.alt) {
            return;
        }

        var title = document.createElement('div');

        title.innerHTML = img.alt;
        title.className = 'img-title';
        title.style = 'padding: 5px; background: black; color: white; font-weight: bold; opacity: 0.9; position: absolute; top: 0;';

        img.parentNode.insertBefore(title, img.nextSlibing);
    });
}, 2000);