fade-in-elements-after-page-load-completion.js

document.addEventListener("DOMContentLoaded", function() {
    var elems = document.getElementsByClassName("fadein-after-load");
    for (var i = 0; i < elems.length; i++) {
        (function() {
            var elem = elems.item(i);
            elem.style.transition = "";
            elem.style.opacity = 0;
            window.addEventListener("load", function() {
                var duration = elem.getAttribute("data-duration");
                duration = duration || "0.5s";
                elem.style.transition = "opacity " + duration;
                elem.style.opacity = 1;
            });
        })();
    }
});