https://www.imperium-aeternum.com/wp-content/themes/darkelements/js/nav.js?ver=7.1.2

1/*
2 * DISPLAY MOBILE NAV
3 */
4
5window.addEventListener('DOMContentLoaded', function() {
6	if ( document.getElementById("mobile-nav") ) {
7		// Hide mobile menu by default
8		document.getElementById("mobile-nav").style.display = 'none';
9		let sub = document.getElementById("mobile-nav").getElementsByClassName("sub-menu");
10		for (let index = 0; index < sub.length; ++index) {
11			sub[index].style.display = 'none';
12		}
13
14		// Display mobile menu when clicked
15		let toggle = document.getElementById("mobile-nav-toggle");
16		toggle.addEventListener('click', function() {
17			let nav = document.getElementById("mobile-nav");
18			nav.style.display = (nav.style.display == 'block') ? 'none' : 'block';
19		});
20
21		// Add toggle and display mobile submenu
22		let a = document.getElementById("mobile-nav").querySelectorAll('.menu-item-has-children > a, .page_item_has_children > a');
23		for( let index = 0; index < a.length; index++ ) {
24			let button = document.createElement('button'); button.className = 'subnav-toggle'; button.innerHTML = '+';
25			a[index].parentNode.insertBefore(button, a[index].nextSibling);
26			button.addEventListener('click', function() {
27				let sub = this.parentNode.getElementsByTagName("ul")[0];
28				sub.style.display = (sub.style.display == 'block') ? 'none' : 'block';
29			});
30		};
31	};
32});