add_filter( 'wp_footer', function() { ?>

	<script>
		( function( $ ) {
			'use strict';
			$( document ).on( 'ready', function() {
				$( '.wpex-mobile-menu li.menu-item-has-children > a' ).each( function() {
					var $this = $( this );
					$this.attr( 'tabindex', 0 ); // lets give the links a tabindex
					$this.live( 'keyup', function( e ) {
						var code = e.keyCode || e.which;
						if ( code === 9 ) {  // 9 is the js key code for tab
							$( this ).find( '> .wpex-open-submenu' ).trigger( 'click' ); // toggle the dropdown function whenever we tab onto a link that has submenus
						}
					} );
				} );
			} );
		} ( jQuery ) );
	</script>

<?php }, 99 );