Add "skip to content", "skip to navigation" links (#38006)

app/javascript/mastodon/features/ui/components/columns_area.jsx

@@ -1,5 +1,5 @@
 import PropTypes from 'prop-types';
-import { Children, cloneElement, useCallback } from 'react';
+import { Children, cloneElement, createContext, useContext, useCallback } from 'react';
 
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import ImmutablePureComponent from 'react-immutable-pure-component';
@@ -53,6 +53,13 @@ const TabsBarPortal = () => {
   return <div id='tabs-bar__portal' ref={setRef} />;
 };
 
+// Simple context to allow column children to know which column they're in
+export const ColumnIndexContext = createContext(1);
+/**
+ * @returns {number}
+ */
+export const useColumnIndexContext = () => useContext(ColumnIndexContext);
+
 export default class ColumnsArea extends ImmutablePureComponent {
   static propTypes = {
     columns: ImmutablePropTypes.list.isRequired,
@@ -140,18 +147,22 @@ export default class ColumnsArea extends ImmutablePureComponent {
 
     return (
       <div className={`columns-area ${ isModalOpen ? 'unscrollable' : '' }`} ref={this.setRef}>
-        {columns.map(column => {
+        {columns.map((column, index) => {
           const params = column.get('params', null) === null ? null : column.get('params').toJS();
           const other  = params && params.other ? params.other : {};
 
           return (
-            <Bundle key={column.get('uuid')} fetchComponent={componentMap[column.get('id')]} loading={this.renderLoading(column.get('id'))} error={this.renderError}>
-              {SpecificComponent => <SpecificComponent columnId={column.get('uuid')} params={params} multiColumn {...other} />}
-            </Bundle>
+            <ColumnIndexContext.Provider value={index} key={column.get('uuid')}>
+              <Bundle fetchComponent={componentMap[column.get('id')]} loading={this.renderLoading(column.get('id'))} error={this.renderError}>
+                {SpecificComponent => <SpecificComponent columnId={column.get('uuid')} params={params} multiColumn {...other} />}
+              </Bundle>
+            </ColumnIndexContext.Provider>
           );
         })}
 
-        {Children.map(children, child => cloneElement(child, { multiColumn: true }))}
+        <ColumnIndexContext.Provider value={columns.size}>
+          {Children.map(children, child => cloneElement(child, { multiColumn: true }))}
+        </ColumnIndexContext.Provider>
       </div>
     );
   }

app/javascript/mastodon/features/ui/components/skip_links/index.tsx

@@ -0,0 +1,84 @@
+import { useCallback, useId } from 'react';
+
+import { useIntl } from 'react-intl';
+
+import { useAppSelector } from 'mastodon/store';
+
+import classes from './skip_links.module.scss';
+
+export const getNavigationSkipLinkId = () => 'skip-link-target-nav';
+export const getColumnSkipLinkId = (index: number) =>
+  `skip-link-target-content-${index}`;
+
+export const SkipLinks: React.FC<{
+  multiColumn: boolean;
+  onFocusGettingStartedColumn: () => void;
+}> = ({ multiColumn, onFocusGettingStartedColumn }) => {
+  const intl = useIntl();
+  const columnCount = useAppSelector((state) => {
+    const settings = state.settings as Immutable.Collection<string, unknown>;
+    return (settings.get('columns') as Immutable.Map<number, unknown>).size;
+  });
+
+  const focusMultiColumnNavbar = useCallback(
+    (e: React.MouseEvent) => {
+      e.preventDefault();
+      onFocusGettingStartedColumn();
+    },
+    [onFocusGettingStartedColumn],
+  );
+
+  return (
+    <ul className={classes.list}>
+      <li className={classes.listItem}>
+        <SkipLink target={getColumnSkipLinkId(1)} hotkey='1'>
+          {intl.formatMessage({
+            id: 'skip_links.skip_to_content',
+            defaultMessage: 'Skip to main content',
+          })}
+        </SkipLink>
+      </li>
+      <li className={classes.listItem}>
+        <SkipLink
+          target={multiColumn ? `/getting-started` : getNavigationSkipLinkId()}
+          onRouterLinkClick={multiColumn ? focusMultiColumnNavbar : undefined}
+          hotkey={multiColumn ? `${columnCount}` : '2'}
+        >
+          {intl.formatMessage({
+            id: 'skip_links.skip_to_navigation',
+            defaultMessage: 'Skip to main navigation',
+          })}
+        </SkipLink>
+      </li>
+    </ul>
+  );
+};
+
+const SkipLink: React.FC<{
+  children: string;
+  target: string;
+  onRouterLinkClick?: React.MouseEventHandler;
+  hotkey: string;
+}> = ({ children, hotkey, target, onRouterLinkClick }) => {
+  const intl = useIntl();
+  const id = useId();
+  return (
+    <>
+      <a href={`#${target}`} aria-describedby={id} onClick={onRouterLinkClick}>
+        {children}
+      </a>
+      <span id={id} className={classes.hotkeyHint}>
+        {intl.formatMessage(
+          {
+            id: 'skip_links.hotkey',
+            defaultMessage: '<span>Hotkey</span> {hotkey}',
+          },
+          {
+            hotkey,
+            span: (text) => <span className='sr-only'>{text}</span>,
+          },
+        )}
+      </span>
+    </>
+  );
+};

app/javascript/mastodon/features/ui/components/skip_links/skip_links.module.scss

@@ -0,0 +1,64 @@
+.list {
+  position: fixed;
+  z-index: 100;
+  margin: 10px;
+  padding: 10px 16px;
+  border-radius: 10px;
+  font-size: 15px;
+  color: var(--color-text-primary);
+  background: var(--color-bg-primary);
+  box-shadow: var(--dropdown-shadow);
+
+  /* Hide visually when not focused */
+  &:not(:focus-within) {
+    width: 1px;
+    height: 1px;
+    margin: 0;
+    padding: 0;
+    clip-path: inset(50%);
+    overflow: hidden;
+  }
+}
+
+.listItem {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding-inline-end: 4px;
+  border-radius: 4px;
+
+  &:not(:first-child) {
+    margin-top: 2px;
+  }
+
+  &:focus-within {
+    outline: var(--outline-focus-default);
+    background: var(--color-bg-brand-softer);
+  }
+
+  :any-link {
+    display: block;
+    padding: 8px;
+    color: inherit;
+    text-decoration-color: var(--color-text-secondary);
+    text-underline-offset: 0.2em;
+
+    &:focus,
+    &:focus-visible {
+      outline: none;
+    }
+  }
+}
+
+.hotkeyHint {
+  display: inline-block;
+  box-sizing: border-box;
+  min-width: 2.5ch;
+  margin-inline-start: auto;
+  padding: 3px 5px;
+  font-family: 'Courier New', Courier, monospace;
+  text-align: center;
+  background: var(--color-bg-primary);
+  border: 1px solid var(--color-border-primary);
+  border-radius: 4px;
+}

app/javascript/mastodon/features/ui/index.jsx

@@ -92,6 +92,7 @@ import { WrappedSwitch, WrappedRoute } from './util/react_router_helpers';
 // Without this it ends up in ~8 very commonly used bundles.
 import '../../components/status';
 import { areCollectionsEnabled } from '../collections/utils';
+import { getNavigationSkipLinkId, SkipLinks } from './components/skip_links';
 
 const messages = defineMessages({
   beforeUnload: { id: 'ui.beforeunload', defaultMessage: 'Your draft will be lost if you leave Mastodon.' },
@@ -253,9 +254,9 @@ class SwitchingColumnsArea extends PureComponent {
             <WrappedRoute path='/lists' component={Lists} content={children} />
             {areCollectionsEnabled() &&
               [
-                <WrappedRoute path={['/collections/new', '/collections/:id/edit']} component={CollectionsEditor} content={children} />,
-                <WrappedRoute path='/collections/:id' component={CollectionDetail} content={children} />,
-                <WrappedRoute path='/collections' component={Collections} content={children} />
+                <WrappedRoute path={['/collections/new', '/collections/:id/edit']} component={CollectionsEditor} content={children} key='collections-editor' />,
+                <WrappedRoute path='/collections/:id' component={CollectionDetail} content={children} key='collections-detail' />,
+                <WrappedRoute path='/collections' component={Collections} content={children} key='collections-list' />
               ]
             }
             <Route component={BundleColumnError} />
@@ -556,6 +557,14 @@ class UI extends PureComponent {
 
   handleHotkeyGoToStart = () => {
     this.props.history.push('/getting-started');
+    // Set focus to the navigation after a timeout
+    // to allow for it to be displayed first
+    setTimeout(() => {
+      const navbarSkipTarget = document.querySelector(
+        `#${getNavigationSkipLinkId()}`,
+      );
+      navbarSkipTarget?.focus();
+    }, 0);
   };
 
   handleHotkeyGoToFavourites = () => {
@@ -617,6 +626,10 @@ class UI extends PureComponent {
     return (
       <Hotkeys global handlers={handlers}>
         <div className={classNames('ui', { 'is-composing': isComposing })} ref={this.setRef}>
+          <SkipLinks
+            multiColumn={layout === 'multi-column'}
+            onFocusGettingStartedColumn={this.handleHotkeyGoToStart}
+          />
           <SwitchingColumnsArea
             identity={this.props.identity}
             location={location}

app/javascript/mastodon/features/ui/util/focusUtils.ts

@@ -1,3 +1,8 @@
+import {
+  getColumnSkipLinkId,
+  getNavigationSkipLinkId,
+} from '../components/skip_links';
+
 /**
  * Out of a list of elements, return the first one whose top edge
  * is inside of the viewport, and return the element and its BoundingClientRect.
@@ -20,9 +25,29 @@ function findFirstVisibleWithRect(
   return null;
 }
 
+function focusColumnTitle(index: number, multiColumn: boolean) {
+  if (multiColumn) {
+    const column = document.querySelector(`.column:nth-child(${index})`);
+    if (column) {
+      column
+        .querySelector<HTMLAnchorElement>(
+          `#${getColumnSkipLinkId(index - 1)}, #${getNavigationSkipLinkId()}`,
+        )
+        ?.focus();
+    }
+  } else {
+    const idSelector =
+      index === 2
+        ? `#${getNavigationSkipLinkId()}`
+        : `#${getColumnSkipLinkId(1)}`;
+
+    document.querySelector<HTMLAnchorElement>(idSelector)?.focus();
+  }
+}
+
 /**
  * Move focus to the column of the passed index (1-based).
- * Focus is placed on the topmost visible item
+ * Focus is placed on the topmost visible item, or the column title
  */
 export function focusColumn(index = 1) {
   // Skip the leftmost drawer in multi-column mode
@@ -35,11 +60,21 @@ export function focusColumn(index = 1) {
     `.column:nth-child(${index + indexOffset})`,
   );
 
-  if (!column) return;
+  function fallback() {
+    focusColumnTitle(index + indexOffset, isMultiColumnLayout);
+  }
+
+  if (!column) {
+    fallback();
+    return;
+  }
 
   const container = column.querySelector('.scrollable');
 
-  if (!container) return;
+  if (!container) {
+    fallback();
+    return;
+  }
 
   const focusableItems = Array.from(
     container.querySelectorAll<HTMLElement>(
@@ -50,20 +85,23 @@ export function focusColumn(index = 1) {
   // Find first item visible in the viewport
   const itemToFocus = findFirstVisibleWithRect(focusableItems);
 
-  if (itemToFocus) {
-    const viewportWidth =
-      window.innerWidth || document.documentElement.clientWidth;
-    const { item, rect } = itemToFocus;
-
-    if (
-      container.scrollTop > item.offsetTop ||
-      rect.right > viewportWidth ||
-      rect.left < 0
-    ) {
-      itemToFocus.item.scrollIntoView(true);
-    }
-    itemToFocus.item.focus();
+  if (!itemToFocus) {
+    fallback();
+    return;
   }
+
+  const viewportWidth =
+    window.innerWidth || document.documentElement.clientWidth;
+  const { item, rect } = itemToFocus;
+
+  if (
+    container.scrollTop > item.offsetTop ||
+    rect.right > viewportWidth ||
+    rect.left < 0
+  ) {
+    itemToFocus.item.scrollIntoView(true);
+  }
+  itemToFocus.item.focus();
 }
 
 /**