mattrbld/js/dropdown.js

const dropdowns = document.querySelectorAll(".dropdown");

const openDropdown = function(input, ul) {
	input.ariaExpanded = "true";
	input.setAttribute("checked", "");
	ul.ariaHidden = "false";
}

const closeDropdown = function(input, ul) {
	input.ariaExpanded = "false";
	input.removeAttribute("checked");
	ul.ariaHidden = "true";
}

for (const dropdown of dropdowns) {
	const input = dropdown.querySelector("input");
	const ul = dropdown.querySelector("ul");

	const lis = ul.querySelectorAll("li");
	const firstItem = lis[0];
	const lastItem = lis[lis.length - 1];

	/* start state */
	input.ariaExpanded = "false";
	ul.ariaHidden = "true";
}