$$plugins.define('initialize', function (element, options) {
    //triggerButton: data-trigger-initialize
    //content to be initialized: data-content-initialize

    const triggerButton = element.getAttribute('data-trigger-initialize'),
        content = document.querySelector(`[data-content-initialize='${triggerButton}']`);

    element.addEventListener('click', function (event) {
        content.classList.add("initialized");
    });
});