$(function () {
    _.map($('[data-widget-collection=data-widget-collection]'), function (node) {
        let observer = new MutationObserver(function (mutations) {
            mutations.forEach(function (mutation) {
                if (mutation.addedNodes.length) {
                    console.log(mutation);
                }
            });
        });

        observer.observe(node, {subtree: true, childList: true});
    });
});