Accessible WordPress Navigation Menu

accessible-menu.php

<div class="menu-container">
    <button class="menu-button" aria-controls="site-header-menu"><span class="screen-reader-text"><?php esc_html_e('Menu','rwc'); ?></span></button>
    <div id="site-header-menu" class="site-header-menu">
      <nav id="site-navigation" class="main-navigation" role="navigation" aria-label="<?php esc_attr_e('Primary Menu', 'rwc'); ?>">
      <?php
      wp_nav_menu(array(
        'theme_location'  => 'primary',
        'depth'           => 3,
        'menu_id'         => 'primary-menu',
        'container_class' => 'nav-primary'
        ));
      ?>
      </nav>
    </div>
</div>

script.js

/**
 * An accessible menu for WordPress
 */

(function($) {

	var menuContainer    = $('.menu-container');
	var menuToggle       = menuContainer.find( '.menu-button' );
	var siteHeaderMenu   = menuContainer.find( '#site-header-menu' );
	var siteNavigation   = menuContainer.find( '#site-navigation' );

	// Toggles the menu button.
	(function() {

		if (!menuToggle.length) {
			return;
		}

		// Add aria-expanded attribute to the menu.
		menuToggle.add(siteNavigation).attr('aria-expanded', 'false');

		// Toggle the menu button.
		menuToggle.on('click', function() {

			// Add toggled-on class.
			$(this).add(siteHeaderMenu).toggleClass('toggled-on');

			// Add aria-expanded attribute value to the menu.
			$(this).add( siteNavigation )
			.attr('aria-expanded', $( this )
			.add( siteNavigation ).attr( 'aria-expanded' ) === 'false' ? 'true' : 'false' );
		} );
	} )();

	// Add the dropdown toggle button to menu items that have children menu items.
	$('.menu-item-has-children > a').not(this).each(function(){

		// Get link text to prepend to screen reader text.
		var linkText = $(this).text();

		// Define screen reader text.
		var screenReaderText = {"expand":": submenu","collapse":": submenu"};

		// Set submenu button with screen reader text
		var dropdownToggle   = $('<button />', {'class': 'dropdown-toggle','aria-expanded': false})
		.append($('<span />', {'class': 'screen-readers',text: linkText+screenReaderText.expand}));

		// Add submenu button after link
		$(this).after(dropdownToggle);
	});

	// Adds aria attribute to the site menu.
	siteHeaderMenu.find( '.menu-item-has-children' ).attr( 'aria-haspopup', 'true' );

	// Toggles the submenu when dropdown toggle button is clicked.
	siteHeaderMenu.find( '.dropdown-toggle' ).click( function(e) {

		// close open submenus and reset attributes.
		$('.dropdown-toggle').not(this).each(function(){
			$(this).removeClass( 'toggled-on' );
			$(this).nextAll( '.sub-menu' ).removeClass( 'toggled-on' );
			$(this).attr( 'aria-expanded', $(this).hasClass( 'toggled-on' ) === 'false' ? 'true' : 'false' );
		});

		// open current submenu and set attributes.
		e.preventDefault();
		$(this).toggleClass( 'toggled-on' );
		$(this).nextAll( '.sub-menu' ).toggleClass( 'toggled-on' );

		$(this).attr( 'aria-expanded', $(this).attr( 'aria-expanded' ) === 'false'
		? 'true' : 'false' );
	});

	// Adds a class to sub-menus for styling.
	$('.sub-menu .menu-item-has-children').parent('.sub-menu').addClass('has-sub-menu');

	// Keyboard navigation.
	$('.menu-item a, button.dropdown-toggle').on('keydown', function(e) {

		if ([37,38,39,40,27].indexOf(e.keyCode) == -1) {
			return;
		}

		switch(e.keyCode) {

			case 27: // escape key
				
				$(this).parents('ul').first().prev('.dropdown-toggle.toggled-on').focus();
				$(this).parents('ul').first().prev('.dropdown-toggle.toggled-on').click();

				break;

			case 37: 				// left key
				e.preventDefault();
				e.stopPropagation();

				if ($(this).hasClass('dropdown-toggle')){
					$(this).prev('a').focus();
				}
				else {
					if ($(this).parent().prev().children('button.dropdown-toggle').length) {
						$(this).parent().prev().children('button.dropdown-toggle').focus();
					}
					else {
						$(this).parent().prev().children('a').focus();
					}
				}

				if ($(this).is('ul ul ul.sub-menu.toggled-on li:first-child a')) {
					$(this).parents('ul.sub-menu.toggled-on li').children('button.dropdown-toggle').focus();
				}

				break;

			case 39: 				// right key
				e.preventDefault();
				e.stopPropagation();

				if($(this).next('button.dropdown-toggle').length) {
					$(this).next('button.dropdown-toggle').focus();
				}
				else {
					$(this).parent().next().children('a').focus();
				}

				if ($(this).is('ul.sub-menu .dropdown-toggle.toggled-on')){
					$(this).parent().find('ul.sub-menu li:first-child a').focus();
				}

				break;


		   case 40: 				// down key
				e.preventDefault();
				e.stopPropagation();

				if($(this).next().length){
					$(this).next().find('li:first-child a').first().focus();
				} else {
					$(this).parent().next().children('a').focus();
				}

				if (($(this).is('ul.sub-menu a')) && ($(this).next('button.dropdown-toggle').length)) {
					$(this).parent().next().children('a').focus();
				}

				if (($(this).is('ul.sub-menu .dropdown-toggle')) && ($(this).parent().next().children('.dropdown-toggle').length)) {
					$(this).parent().next().children('.dropdown-toggle').focus();
				}

				break;


			case 38: 				// up key
				e.preventDefault();
				e.stopPropagation();

				if($(this).parent().prev().length){
					$(this).parent().prev().children('a').focus();
				} else {
					$(this).parents('ul').first().prev('.dropdown-toggle.toggled-on').focus();
				}

				if (($(this).is('ul.sub-menu .dropdown-toggle')) && ($(this).parent().prev().children('.dropdown-toggle').length)) {
					$(this).parent().prev().children('.dropdown-toggle').focus();
				}

				break;
				
		}
	});
})(jQuery);

style.scss

.menu-container:after {
	display: table;
	clear: both;
	content: "";
}

.site-header-menu {
	display: none;
	font-size: 1rem;
	clear: both;
}

.main-navigation ul {
	margin: 0;
	padding: 0;
	list-style: none;
}

.main-navigation ul li {
	margin-right: 40px;
	margin-bottom: 10px;
	min-height: 30px;
}

.main-navigation ul a,
.main-navigation ul a:visited {
	border: none;
	color: $black;
	font-size: 16px;
	font-weight: 400;
	line-height: 22px;
	position: relative;
	text-decoration: none;
	text-transform: uppercase;
}

.main-navigation ul a:hover {
	border-bottom: 3px solid;
}

.main-navigation ul ul {
	display: none;
	margin-top: 0px;
	margin-left: 25px;
}

.main-navigation ul ul li{
	a{
		font-size: 14px;
		text-transform: none;
		padding: 0;
		margin-bottom: 10px;
		border-bottom: solid 4px transparent;
		padding-bottom: 2px;
	}
	&:last-child{
		padding-bottom: 0;
		a{
			margin-bottom: 0;
		}
	}
	&:hover > a {
		background: $neutral_200;
	}
}

.main-navigation ul ul ul {
	display: none;
	margin-left: 25px;
}

.no-js .site-header-menu,
.site-header-menu.toggled-on {
	display: block;
}

.site-header-menu.toggled-on {
	margin-top: 10px;
}

.no-js .main-navigation ul,
.main-navigation ul .sub-menu.toggled-on {
	display: block;
}

button.dropdown-toggle,
button.menu-button {
	display: inline;
	background-color: transparent;
	border: 0;
	-webkit-appearance: none;
	-moz-appearance: none;
	cursor: pointer;
	content: "";
}

button.dropdown-toggle {
	width: 25px;
	height: 25px;
	position: absolute;
	right: 15px;
	margin-left: 10px;
	padding: 2px;
}

.dropdown-toggle:after,
.dropdown-toggle.toggled-on:after {
	font-size: 1rem;
}

.menu-button {
	width: 25px;
	height: 25px;
	float: right;
	padding: 0 !important;
	font-size: 1.35rem;
	margin-top: 25px;
	padding: 5px 5px 5px 5px;
}

.main-navigation a:focus,
button.dropdown-toggle:focus,
button.menu-button:focus {
	outline: 1px solid $black;
	outline-offset: 2px;
}

.no-js .menu-button {
	display: none;
}

/* Plus symbol to expand sub-menu on mobile */
.dropdown-toggle:after {
	content: "\002B";
}

/* Minus symbol to collapse sub-menu on mobile */
.dropdown-toggle.toggled-on:after {
	content: "\2212";
}

/* 'Hamburger' or bars to expand menu on mobile*/
.menu-button:before {
	content: "\f0c9";
	font-family: "Font Awesome 6 Free"; font-weight: 400;
}

/* Times (x) to collapse menu on mobile*/
.menu-button.toggled-on:before {
	content: "\f00d";
	font-family: "Font Awesome 6 Free"; font-weight: 400;
}

.dropdown-toggle:after,
.dropdown-toggle.toggled-on:after,
.menu-button:before,
.menu-button.toggled-on:before {
	font-weight: bold;
}

/* Screen readers */
.screen-readers {
	position: absolute !important;
	width: 1px;
	height: 1px;
	margin: -1px;
	padding: 0;
	border: 0;
	word-break: normal !important;
	overflow: hidden;
	clip: rect(0 0 0 0);
}

/* Desktop media query */
@media only screen and (min-width: 768px) {
	button.menu-button {
		display: none;
	}
	.menu-container {
		padding-top: 0;
		padding-bottom: 0;
		padding-left: 0;
	}
	.site-header-menu {
		display: block;
		margin-left: 10px;
	float: right;
	//margin-top: 30px;
	clear: none;
	}
	.main-navigation ul {
		position: relative;
		float: left;
	}
	.main-navigation ul li {
		position: relative;
		float: left;
		margin: 0;
		padding: 10px;
	min-height: 0px;
	}
	.no-js .main-navigation ul ul,
	.main-navigation ul ul {
		position: absolute;
		display: none;
		top: 100%;
		left: 0;
		padding: 0;
		z-index: 999;

	background: $white;
	border-radius: 15px;
	padding: 25px;
	}
	.no-js .main-navigation ul ul li,
	.main-navigation ul ul li {
		float: none;
		width: 175px;
		padding: 0;
		padding-bottom: 15px;
	}
	.main-navigation ul .has-sub-menu > li {
		padding-right: 40px;
	}
	.no-js .main-navigation ul ul ul,
	.main-navigation ul ul ul {
		top: -1px;
		left: 100%;
		margin-left: 0;
		margin-top: -5px;
	}
	ul.sub-menu .dropdown-toggle {
		position: absolute;
		right: 10px;
		top: 4px;
	}

	/* Arrow down */
	.main-navigation ul .dropdown-toggle:after {
		content: "\f078";
	font-family: "Font Awesome 6 Free"; font-weight: 400;
	font-size: .75rem;
	}

	/* Arrow right */
	.main-navigation ul ul .dropdown-toggle:after {
		content: "\f054";
	font-family: "Font Awesome 6 Free"; font-weight: 400;
	font-size: .75rem;
	}

	/* Arrow up */
	.main-navigation ul .dropdown-toggle.toggled-on:after {
		content: "\f077";
		font-family: "Font Awesome 6 Free"; font-weight: 400;
	}

	/* Arrow left */
	.main-navigation ul ul .dropdown-toggle.toggled-on:after {
		content: "\f053";
		font-family: "Font Awesome 6 Free"; font-weight: 400;
	}

	.main-navigation ul .dropdown-toggle:after,
	.main-navigation ul ul .dropdown-toggle:after,
	.main-navigation ul .dropdown-toggle.toggled-on:after,
	.main-navigation ul ul .dropdown-toggle.toggled-on:after {
		font-weight: bold;
	}

	button.dropdown-toggle {
		width: auto;
		height: auto;
		position: inherit;
		right: auto;
	}
	.main-navigation ul li:hover > ul {
		display: block;
	}
}