document.addEventListener('DOMContentLoaded', function () { var acc = document.getElementsByClassName('f_accordion'); var i; for (i = 0; i < acc.length; i++) { acc[i].addEventListener('click', function () { this.classList.toggle('active'); var panel = this.nextElementSibling; if (panel.style.maxHeight) { panel.style.maxHeight = null; } else { panel.style.maxHeight = panel.scrollHeight + 'px'; } }); } });