https://cinespia.org/wp-content/themes/cinespia/js/small-menu.js?ver=20120206

1/**
2 * navigation.js
3 *
4 * Handles toggling the navigation menu for small screens.
5 */
6( function() {
7	var container = document.getElementById( 'navigation' ),
8	    button    = container.getElementsByTagName( 'h1' )[0],
9	    menu      = container.getElementsByTagName( 'ul' )[0];
10
11	if ( undefined == button || undefined == menu )
12		return false;
13
14	button.onclick = function() {
15		if ( -1 == menu.className.indexOf( 'nav-menu' ) )
16			menu.className = 'nav-menu';
17
18		if ( -1 != button.className.indexOf( 'toggled-on' ) ) {
19			button.className = button.className.replace( ' toggled-on', '' );
20			menu.className = menu.className.replace( ' toggled-on', '' );
21			container.className = container.className.replace( 'main-small-navigation', 'navigation-main' );
22		} else {
23			button.className += ' toggled-on';
24			menu.className += ' toggled-on';
25			container.className = container.className.replace( 'navigation-main', 'main-small-navigation' );
26		}
27	};
28
29	// Hide menu toggle button if menu is empty.
30	if ( ! menu.childNodes.length )
31		button.style.display = 'none';
32} )();