feat: improve focus selector perf with focus-visible and focus-within polyfill

apps/vr-tests-react-components/src/stories/Link.stories.tsx

@@ -14,12 +14,10 @@ storiesOf('Link Converged - Rendered as anchor', module)
         .hover('.fui-Link')
         .snapshot('hover', { cropTo: '.testWrapper' })
         // This needs to be added so that the focus outline is shown correctly
-        .executeScript(
-          "document.getElementsByClassName('fui-FluentProvider')[0].setAttribute('data-keyboard-nav', true)",
-        )
+        .executeScript("document.getElementsByClassName('fui-Link')[0].classList.add('fui-focus-visible')")
         .focus('.fui-Link')
         .snapshot('focused', { cropTo: '.testWrapper' })
-        .executeScript("document.getElementsByClassName('fui-FluentProvider')[0].removeAttribute('data-keyboard-nav')")
+        .executeScript("document.getElementsByClassName('fui-Link')[0].classList.remove('fui-focus-visible')")
         .mouseDown('.fui-Link')
         .snapshot('pressed', { cropTo: '.testWrapper' })
         .mouseUp('.fui-Link')
@@ -96,12 +94,10 @@ storiesOf('Link Converged - Rendered as button', module)
         .hover('.fui-Link')
         .snapshot('hover', { cropTo: '.testWrapper' })
         // This needs to be added so that the focus outline is shown correctly
-        .executeScript(
-          "document.getElementsByClassName('fui-FluentProvider')[0].setAttribute('data-keyboard-nav', true)",
-        )
+        .executeScript("document.getElementsByClassName('fui-Link')[0].classList.add('fui-focus-visible')")
         .focus('.fui-Link')
         .snapshot('focused', { cropTo: '.testWrapper' })
-        .executeScript("document.getElementsByClassName('fui-FluentProvider')[0].removeAttribute('data-keyboard-nav')")
+        .executeScript("document.getElementsByClassName('fui-Link')[0].classList.remove('fui-focus-visible')")
         .mouseDown('.fui-Link')
         .snapshot('pressed', { cropTo: '.testWrapper' })
         .mouseUp('.fui-Link')

change/@fluentui-react-checkbox-25fb0c36-d07f-4a39-bd82-831bb2b756b0.json

@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "refactor: use `useFocusWithin` hook for :focus-within styles",
+  "packageName": "@fluentui/react-checkbox",
+  "email": "[email protected]",
+  "dependentChangeType": "patch"
+}

change/@fluentui-react-portal-2940da05-fb94-4cac-8763-6e0c4a14ee8f.json

@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "fix: use `useFocusVisible` hook for :focus-visible styles",
+  "packageName": "@fluentui/react-portal",
+  "email": "[email protected]",
+  "dependentChangeType": "patch"
+}

change/@fluentui-react-provider-9ddc6123-46e0-4094-9670-659f00f241b8.json

@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "fix: use `useFocusVisible` hook for :focus-visible styles",
+  "packageName": "@fluentui/react-provider",
+  "email": "[email protected]",
+  "dependentChangeType": "patch"
+}

change/@fluentui-react-radio-36321438-6ccb-4827-85da-098c7e6c76cf.json

@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "refactor: use `useFocusWithin` hook for :focus-within styles",
+  "packageName": "@fluentui/react-radio",
+  "email": "[email protected]",
+  "dependentChangeType": "patch"
+}

change/@fluentui-react-slider-e562a2af-50fe-4b42-9eec-003613926997.json

@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "refactor: use `useFocusWithin` hook for :focus-within styles",
+  "packageName": "@fluentui/react-slider",
+  "email": "[email protected]",
+  "dependentChangeType": "patch"
+}

change/@fluentui-react-switch-504a98f0-bdbd-4377-959c-1dcb2275040a.json

@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "refactor: use `useFocusWithin` hook for :focus-within styles",
+  "packageName": "@fluentui/react-switch",
+  "email": "[email protected]",
+  "dependentChangeType": "patch"
+}

change/@fluentui-react-tabster-897f1851-6bb3-4082-8a54-ace4ca191faf.json

@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "feat: create `:focus-visible` and `:focus-within` polyfills",
+  "packageName": "@fluentui/react-tabster",
+  "email": "[email protected]",
+  "dependentChangeType": "patch"
+}

packages/react-components/react-checkbox/src/components/Checkbox/useCheckbox.tsx

@@ -17,6 +17,7 @@ import {
   CircleFilled,
 } from '@fluentui/react-icons';
 import { Label } from '@fluentui/react-label';
+import { useFocusWithin } from '@fluentui/react-tabster';
 
 /**
  * Create the state required to render Checkbox.
@@ -69,7 +70,10 @@ export const useCheckbox_unstable = (props: CheckboxProps, ref: React.Ref<HTMLIn
     },
     root: resolveShorthand(props.root, {
       required: true,
-      defaultProps: nativeProps.root,
+      defaultProps: {
+        ref: useFocusWithin<HTMLSpanElement>(),
+        ...nativeProps.root,
+      },
     }),
     input: resolveShorthand(props.input, {
       required: true,

packages/react-components/react-portal/src/components/Portal/usePortalMountNode.ts

@@ -4,8 +4,8 @@ import {
   useThemeClassName_unstable as useThemeClassName,
   useFluent_unstable as useFluent,
 } from '@fluentui/react-shared-contexts';
-import { useKeyboardNavAttribute } from '@fluentui/react-tabster';
 import { makeStyles, mergeClasses } from '@griffel/react';
+import { useFocusVisible } from '@fluentui/react-tabster';
 
 export type UsePortalMountNodeOptions = {
   /**
@@ -26,6 +26,7 @@ const useStyles = makeStyles({
  */
 export const usePortalMountNode = (options: UsePortalMountNodeOptions): HTMLElement | null => {
   const { targetDocument, dir } = useFluent();
+  const focusVisibleRef = useFocusVisible<HTMLDivElement>() as React.MutableRefObject<HTMLElement | null>;
 
   const classes = useStyles();
   const themeClassName = useThemeClassName();
@@ -49,15 +50,14 @@ export const usePortalMountNode = (options: UsePortalMountNodeOptions): HTMLElem
 
       element.classList.add(...classesToApply);
       element.setAttribute('dir', dir);
+      focusVisibleRef.current = element;
 
       return () => {
         element.classList.remove(...classesToApply);
         element.removeAttribute('dir');
       };
     }
-  }, [element, className, dir]);
-
-  (useKeyboardNavAttribute() as React.MutableRefObject<HTMLElement>).current = element!;
+  }, [className, dir, element, focusVisibleRef]);
 
   React.useEffect(() => {
     return () => {

packages/react-components/react-provider/src/components/FluentProvider/useFluentProvider.ts

@@ -1,4 +1,4 @@
-import { useKeyboardNavAttribute } from '@fluentui/react-tabster';
+import { useFocusVisible } from '@fluentui/react-tabster';
 import {
   ThemeContext_unstable as ThemeContext,
   useFluent_unstable as useFluent,
@@ -58,7 +58,7 @@ export const useFluentProvider_unstable = (
     root: getNativeElementProps('div', {
       ...props,
       dir,
-      ref: useMergedRefs(ref, useKeyboardNavAttribute()),
+      ref: useMergedRefs(ref, useFocusVisible<HTMLDivElement>()),
     }),
   };
 };

packages/react-components/react-radio/src/components/Radio/useRadio.tsx

@@ -4,6 +4,7 @@ import { Label } from '@fluentui/react-label';
 import { getPartitionedNativeProps, resolveShorthand, useId, useMergedEventCallbacks } from '@fluentui/react-utilities';
 import { RadioGroupContext } from '../../contexts/RadioGroupContext';
 import { useContextSelector } from '@fluentui/react-context-selector';
+import { useFocusWithin } from '@fluentui/react-tabster';
 import type { RadioProps, RadioState } from './Radio.types';
 
 /**
@@ -41,7 +42,10 @@ export const useRadio_unstable = (props: RadioProps, ref: React.Ref<HTMLInputEle
 
   const root = resolveShorthand(props.root, {
     required: true,
-    defaultProps: nativeProps.root,
+    defaultProps: {
+      ref: useFocusWithin<HTMLSpanElement>(),
+      ...nativeProps.root,
+    },
   });
 
   const input = resolveShorthand(props.input, {

packages/react-components/react-slider/src/components/Slider/useSlider.ts

@@ -2,6 +2,7 @@ import * as React from 'react';
 import { getPartitionedNativeProps, resolveShorthand, useId } from '@fluentui/react-utilities';
 import { useSliderState_unstable } from './useSliderState';
 import { SliderProps, SliderState } from './Slider.types';
+import { useFocusWithin } from '@fluentui/react-tabster';
 
 export const useSlider_unstable = (props: SliderProps, ref: React.Ref<HTMLInputElement>): SliderState => {
   const nativeProps = getPartitionedNativeProps({
@@ -34,6 +35,7 @@ export const useSlider_unstable = (props: SliderProps, ref: React.Ref<HTMLInputE
     root: resolveShorthand(root, {
       required: true,
       defaultProps: {
+        ref: useFocusWithin<HTMLDivElement>(),
         ...nativeProps.root,
       },
     }),

packages/react-components/react-switch/src/components/Switch/useSwitch.tsx

@@ -1,6 +1,7 @@
 import * as React from 'react';
 import { CircleFilled } from '@fluentui/react-icons';
 import { Label } from '@fluentui/react-label';
+import { useFocusWithin } from '@fluentui/react-tabster';
 import { getPartitionedNativeProps, resolveShorthand, useId, useMergedEventCallbacks } from '@fluentui/react-utilities';
 import type { SwitchProps, SwitchState } from './Switch.types';
 
@@ -25,7 +26,7 @@ export const useSwitch_unstable = (props: SwitchProps, ref: React.Ref<HTMLInputE
   const id = useId('switch-', nativeProps.primary.id);
 
   const root = resolveShorthand(props.root, {
-    defaultProps: nativeProps.root,
+    defaultProps: { ref: useFocusWithin<HTMLDivElement>(), ...nativeProps.root },
     required: true,
   });
 

packages/react-components/react-tabster/etc/react-tabster.api.md

@@ -5,6 +5,7 @@
 ```ts
 
 import type { GriffelStyle } from '@griffel/react';
+import * as React_2 from 'react';
 import type { RefObject } from 'react';
 import { Types } from 'tabster';
 
@@ -66,6 +67,12 @@ export const useFocusFinders: () => {
     findPrevFocusable: (currentElement: HTMLElement, options?: Pick<Types.FindNextProps, 'container'>) => HTMLElement | null | undefined;
 };
 
+// @public (undocumented)
+export function useFocusVisible<TElement extends HTMLElement = HTMLElement>(): React_2.RefObject<TElement>;
+
+// @public
+export function useFocusWithin<TElement extends HTMLElement = HTMLElement>(): React_2.RefObject<TElement>;
+
 // @public
 export function useKeyboardNavAttribute<E extends HTMLElement>(): RefObject<E>;
 

packages/react-components/react-tabster/src/focus/constants.ts

@@ -1,5 +1,7 @@
 export const KEYBOARD_NAV_ATTRIBUTE = 'data-keyboard-nav' as const;
 export const KEYBOARD_NAV_SELECTOR = `:global([${KEYBOARD_NAV_ATTRIBUTE}])` as const;
+export const FOCUS_VISIBLE_CLASS = 'fui-focus-visible';
+export const FOCUS_WITHIN_CLASS = 'fui-focus-within';
 export const defaultOptions = {
   style: {},
   selector: 'focus',

packages/react-components/react-tabster/src/focus/createCustomFocusIndicatorStyle.ts

@@ -1,4 +1,4 @@
-import { KEYBOARD_NAV_SELECTOR, defaultOptions } from './constants';
+import { FOCUS_VISIBLE_CLASS, defaultOptions, FOCUS_WITHIN_CLASS } from './constants';
 import type { GriffelStyle } from '@griffel/react';
 
 export interface CreateCustomFocusIndicatorStyleOptions {
@@ -19,5 +19,19 @@ export const createCustomFocusIndicatorStyle = (
   ':focus': {
     outlineStyle: 'none',
   },
-  [`${KEYBOARD_NAV_SELECTOR} :${selector}`]: style,
+  ':focus-visible': {
+    outlineStyle: 'none',
+  },
+  // Remove the `.fui-FluentProvider` global selector once Griffel supports chained global styles
+  // https://github.com/microsoft/griffel/issues/178
+  ...(selector === 'focus' && {
+    [`:global(.fui-FluentProvider)`]: {
+      [`& .${FOCUS_VISIBLE_CLASS}`]: style,
+    },
+  }),
+  ...(selector === 'focus-within' && {
+    [`:global(.fui-FluentProvider)`]: {
+      [`& .${FOCUS_WITHIN_CLASS}:${selector}`]: style,
+    },
+  }),
 });

packages/react-components/react-tabster/src/focus/focusVisiblePolyfill.ts

@@ -0,0 +1,105 @@
+import { KEYBORG_FOCUSIN, KeyborgFocusInEvent, createKeyborg, disposeKeyborg } from 'keyborg';
+import { FOCUS_VISIBLE_CLASS } from './constants';
+
+/**
+ * Because `addEventListener` type override falls back to 2nd definition (evt name is unknown string literal)
+ * evt is being typed as a base class of MouseEvent -> `Event`.
+ * This type is used to override `listener` calls to make TS happy
+ */
+type ListenerOverride = (evt: Event) => void;
+
+type FocusVisibleState = {
+  /**
+   * Current element with focus visible in state
+   */
+  current: HTMLElement | undefined;
+};
+
+type HTMLElementWithFocusVisibleScope = {
+  focusVisible: boolean | undefined;
+} & HTMLElement;
+
+export function applyFocusVisiblePolyfill(scope: HTMLElement, win: Window): () => void {
+  if (alreadyInScope(scope)) {
+    // Focus visible polyfill already applied at this scope
+    return () => undefined;
+  }
+
+  const state: FocusVisibleState = {
+    current: undefined,
+  };
+
+  const keyborg = createKeyborg(win);
+
+  // When navigation mode changes remove the focus-visible selector
+  keyborg.subscribe(isNavigatingWithKeyboard => {
+    if (!isNavigatingWithKeyboard && state.current) {
+      removeFocusVisibleClass(state.current);
+      state.current = undefined;
+    }
+  });
+
+  // Keyborg's focusin event is delegated so it's only registered once on the window
+  // and contains metadata about the focus event
+  const keyborgListener = (e: KeyborgFocusInEvent) => {
+    if (state.current) {
+      removeFocusVisibleClass(state.current);
+      state.current = undefined;
+    }
+
+    if (keyborg.isNavigatingWithKeyboard() && isHTMLElement(e.target) && e.target) {
+      // Griffel can't create chained global styles so use the parent element for now
+      state.current = e.target;
+      applyFocusVisibleClass(state.current);
+    }
+  };
+
+  // Make sure that when focus leaves the scope, the focus visible class is removed
+  const blurListener = (e: FocusEvent) => {
+    if (!e.relatedTarget || (isHTMLElement(e.relatedTarget) && !scope.contains(e.relatedTarget))) {
+      if (state.current) {
+        removeFocusVisibleClass(state.current);
+        state.current = undefined;
+      }
+    }
+  };
+
+  scope.addEventListener(KEYBORG_FOCUSIN, keyborgListener as ListenerOverride);
+  scope.addEventListener('focusout', blurListener);
+  (scope as HTMLElementWithFocusVisibleScope).focusVisible = true;
+
+  // Return disposer
+  return () => {
+    scope.removeEventListener(KEYBORG_FOCUSIN, keyborgListener as ListenerOverride);
+    scope.removeEventListener('focusout', blurListener);
+    delete (scope as HTMLElementWithFocusVisibleScope).focusVisible;
+    disposeKeyborg(keyborg);
+  };
+}
+
+function applyFocusVisibleClass(el: HTMLElement) {
+  el.classList.add(FOCUS_VISIBLE_CLASS);
+}
+
+function removeFocusVisibleClass(el: HTMLElement) {
+  el.classList.remove(FOCUS_VISIBLE_CLASS);
+}
+
+function isHTMLElement(target: EventTarget | null): target is HTMLElement {
+  if (!target) {
+    return false;
+  }
+  return Boolean(target && typeof target === 'object' && 'classList' in target && 'contains' in target);
+}
+
+function alreadyInScope(el: HTMLElement | null | undefined): boolean {
+  if (!el) {
+    return false;
+  }
+
+  if ((el as HTMLElementWithFocusVisibleScope).focusVisible) {
+    return true;
+  }
+
+  return alreadyInScope(el?.parentElement);
+}