https://frankgruber.me/wp-content/themes/adventure/js/navigation.js?ver=1.0

1/**
2* navigation.js
3* Licensed under the GPLv2 license.
4* Handles toggling the navigation menu for small screens.
5*/
6( function() {
7
8	var container, button, menu, holder;
9
10	container = document.getElementById( 'navigation' );
11	if ( ! container )
12		return;
13
14	button = container.getElementsByTagName( 'span' )[0];
15	if ( 'undefined' === typeof button )
16		return;
17
18	menu = container.getElementsByTagName( 'ul' )[0];
19
20	// Hide menu toggle button if menu is empty and return early.
21	if ( 'undefined' === typeof menu ) {
22		button.style.display = 'none';
23		return;
24	}
25
26	holder = container.getElementsByTagName( 'div' )[0];
27	if ( 'undefined' === typeof button )
28		return;
29
30	button.onclick = function() {
31		if ( -1 == menu.className.indexOf( 'mobile-menu' ) )
32			menu.className = 'menu';
33
34		if ( -1 != button.className.indexOf( 'toggled-on' ) ) {
35			holder.className += ' sf-js-enabled';
36			button.className = button.className.replace( ' toggled-on', '' );
37			menu.className = menu.className.replace( ' toggled-on', '' );
38			menu.className = menu.className.replace( 'mobile-menu', 'menu' );
39			holder.className = holder.className.replace( 'mobile-menu', 'menu' );
40			container.className = container.className.replace( 'main-small-navigation', 'navigation-main' );
41		} else {
42			button.className += ' toggled-on';
43			menu.className += ' toggled-on';
44			menu.className = menu.className.replace( 'menu', 'mobile-menu' );
45			holder.className = holder.className.replace( 'menu', 'mobile-menu' );
46			holder.className = holder.className.replace( 'sf-js-enabled', '' );
47			container.className = container.className.replace( 'navigation-main', 'main-small-navigation' );
48		}
49	};
50
51} )();