feat(navbar keyboard navigation): optionally navigate to submenu item…

…s using the `Tab` and `Enter` keys. (#3482)

* feat(navbar keyboard navigation): add arrow keys navigation to navbar

* feat(navbar keyboard navigation): add arrow keys navigation to navbar

* feat(navbar keyboard navigation): add event types

* feat(navbar keyboard navigation): cleanup unused code

* feat(navbar keyboard navigation): make Tab and Enter key primarily for keyboard navigation

* feat(navbar keyboard navigation): make Tab and Enter key primarily for keyboard navigation

* feat(navbar keyboard navigation): tabIndex to focus submenu container

* feat(navbar keyboard navigation): update changeset

* feat(navbar keyboard navigation): rename state variable

* feat(navbar keyboard navigation): prevent default enter behaviour

* feat(navbar keyboard navigation): handle submenu state after onBlur

* feat(keyboard navigation): add submenu preview on navigation

* feat(keyboard navigation): remove unused variables

* feat(accessibility): remove unused hook

* feat(main nav accessibility): update focus when navigating to a new submenu

---------

Co-authored-by: Ddouglasz <douglas.egiemeh@gmail.com>

.changeset/small-clouds-exist.md

@@ -0,0 +1,5 @@
+---
+'@commercetools-frontend/application-shell': minor
+---
+
+Improve keyboard accessibility by switching between the menu items and submenu items using mainly the Tab and Enter keys.

packages/application-shell/src/components/navbar/menu-items.tsx

@@ -173,6 +173,7 @@ export type MenuGroupProps = {
   children?: ReactNode;
   submenuVerticalPosition?: number;
   isSubmenuAboveMenuItem?: boolean;
+  handleKeyDown?: React.KeyboardEventHandler<HTMLUListElement>;
 };
 
 const MenuGroup = forwardRef<HTMLUListElement, MenuGroupProps>((props, ref) => {
@@ -189,6 +190,7 @@ const MenuGroup = forwardRef<HTMLUListElement, MenuGroupProps>((props, ref) => {
   const isSublistActiveWhileIsMenuCollapsed = Boolean(
     props.level === 2 && props.isActive && !props.isExpanded
   );
+
   return (
     <MenuList
       ref={ref && props.level === 2 ? ref : null}
@@ -200,6 +202,7 @@ const MenuGroup = forwardRef<HTMLUListElement, MenuGroupProps>((props, ref) => {
         isSublistActiveWhileIsMenuExpanded ||
         isSublistActiveWhileIsMenuCollapsed
       }
+      onKeyDown={props.handleKeyDown}
       className={classnames(
         {
           'sublist-expanded__active': isSublistActiveWhileIsMenuExpanded,
@@ -249,6 +252,7 @@ type MenuItemProps = {
     | FocusEventHandler<HTMLElement>;
   children: ReactNode;
   identifier?: string;
+  onKeyDown?: (e: React.KeyboardEvent<HTMLLIElement>) => void;
 };
 const MenuItem = (props: MenuItemProps) => {
   return (
@@ -259,6 +263,7 @@ const MenuItem = (props: MenuItemProps) => {
       onMouseLeave={props.onMouseLeave as MouseEventHandler<HTMLElement>}
       onFocus={props.onMouseEnter as FocusEventHandler<HTMLElement>}
       onBlur={props.onMouseLeave as FocusEventHandler<HTMLElement>}
+      onKeyDown={props.onKeyDown}
       data-menuitem={props.identifier}
       className={classnames({
         active: props.isActive,
@@ -281,6 +286,7 @@ export type MenuItemLinkProps = {
   onClick?: (event: SyntheticEvent<HTMLAnchorElement>) => void;
   useFullRedirectsForLinks?: boolean;
   isSubmenuLink?: boolean;
+  isSubmenuFocused?: boolean;
 };
 const menuItemLinkDefaultProps: Pick<MenuItemLinkProps, 'exactMatch'> = {
   exactMatch: false,
@@ -306,6 +312,7 @@ const MenuItemLink = (props: MenuItemLinkProps) => {
           activeClassName="highlighted"
           data-link-level={linkLevel}
           css={getMenuItemLinkStyles(Boolean(props.isSubmenuLink))}
+          tabIndex={props.isSubmenuLink && !props.isSubmenuFocused ? -1 : 0}
           onClick={(event) => {
             if (props.linkTo && props.useFullRedirectsForLinks) {
               event.preventDefault();

packages/application-shell/src/components/navbar/navbar.tsx

@@ -111,6 +111,8 @@ const getIsSubmenuRouteActive = (
 export const ApplicationMenu = (props: ApplicationMenuProps) => {
   const [submenuVerticalPosition, setSubmenuVerticalPosition] = useState(0);
   const [isSubmenuAboveMenuItem, setIsSubmenuAboveMenuItem] = useState(false);
+  const [isSubmenuFocused, setIsSubmenuFocused] = useState(false);
+  const observerRef = useRef<IntersectionObserver | null>(null);
   const submenuRef = useRef<HTMLUListElement>(null);
 
   const hasSubmenu =
@@ -149,8 +151,6 @@ export const ApplicationMenu = (props: ApplicationMenuProps) => {
     [menuItemIdentifier, props.isMenuOpen]
   );
 
-  const observerRef = useRef<IntersectionObserver | null>(null);
-
   useLayoutEffect(() => {
     observerRef.current = new IntersectionObserver(callbackFn, {
       rootMargin: '-100% 0px 0px 0px', // we want to observe if the submenu crosses the bottom line of the viewport - therefore we set the root element top margin to -100% of the viewport height
@@ -166,6 +166,7 @@ export const ApplicationMenu = (props: ApplicationMenuProps) => {
     if (observer && currentSubmenuRef) {
       observer.observe(currentSubmenuRef);
     }
+    setIsSubmenuFocused(false);
     return () => observer?.disconnect();
   }, [
     menuItemIdentifier,
@@ -195,6 +196,17 @@ export const ApplicationMenu = (props: ApplicationMenuProps) => {
     ? getMenuVisibilitiesOfSubmenus(props.menu)
     : getMenuVisibilityOfMainmenu(props.menu);
 
+  const handleKeyDown = (e: React.KeyboardEvent<HTMLLIElement>) => {
+    const currentlyFocusedItem = submenuRef.current?.querySelector(':focus');
+
+    if (e.key === 'Enter') {
+      setIsSubmenuFocused(true);
+      if (!currentlyFocusedItem) {
+        submenuRef.current?.querySelector('a')?.focus();
+      }
+    }
+  };
+
   return (
     <RestrictedMenuItem
       key={props.menu.key}
@@ -213,6 +225,7 @@ export const ApplicationMenu = (props: ApplicationMenuProps) => {
         isMainMenuRouteActive={isMainMenuRouteActive}
         isMenuOpen={props.isMenuOpen}
         onClick={props.handleToggleItem}
+        onKeyDown={handleKeyDown}
         onMouseEnter={props.handleToggleItem}
         onMouseLeave={props.shouldCloseMenuFly}
         identifier={menuItemIdentifier}
@@ -282,6 +295,7 @@ export const ApplicationMenu = (props: ApplicationMenuProps) => {
                         }
                         onClick={props.onMenuItemClick}
                         isSubmenuLink
+                        isSubmenuFocused={isSubmenuFocused}
                       >
                         <MenuLabel
                           labelAllLocales={submenu.labelAllLocales}