https://bandodental.jp/navigation.js

1/**
2 * navigation.js
3 *
4 * Handles toggling the navigation menu for small screens.
5 */
6( function() {
7
8	var containers = document.getElementsByClassName( 'button-menu' );
9	var i;
10	for (i = 0; i < containers.length; i++) {
11		set_button_style( containers[i].id );
12	}
13} )();
14
15function set_button_style(id) {
16
17	var container = document.getElementById( id );
18
19	if ( undefined == container )
20		return;
21
22	var button    = container.getElementsByTagName( 'h1' )[0],
23	    menu      = container.getElementsByTagName( 'ul' )[0];
24
25	if ( undefined == button )
26		return;
27
28	if( undefined == menu ) {
29		button.style.display = 'none';
30	} else {
31		button.onclick = function() {
32			if ( -1 != button.className.indexOf( 'toggled-on' ) ) {
33				button.className = button.className.replace( ' toggled-on', '' );
34				menu.className = menu.className.replace( ' toggled-on', '' );
35			} else {
36				button.className += ' toggled-on';
37				menu.className += ' toggled-on';
38			}
39		};
40
41		// Hide menu toggle button if menu is empty.
42		if ( ! menu.childNodes.length )
43			button.style.display = 'none';
44	}
45}