Create useIsMacOS hook for SSR support

packages/react/src/KeybindingHint/components/Chord.tsx

@@ -64,4 +64,7 @@ export const Chord = ({keys, format = 'condensed', variant = 'normal'}: Keybindi
 )
 
 /** Plain string version of `Chord` for use in `aria` string attributes. */
-export const accessibleChordString = (chord: string) => splitChord(chord).map(accessibleKeyName).join(' ')
+export const accessibleChordString = (chord: string, isMacOS: boolean) =>
+  splitChord(chord)
+    .map(key => accessibleKeyName(key, isMacOS))
+    .join(' ')

packages/react/src/KeybindingHint/components/Key.tsx

@@ -2,16 +2,21 @@ import React from 'react'
 import VisuallyHidden from '../../_VisuallyHidden'
 import {accessibleKeyName, condensedKeyName, fullKeyName} from '../key-names'
 import type {KeybindingHintFormat} from '../props'
+import {useIsMacOS} from '../../hooks/useIsMacOS'
 
 interface KeyProps {
   name: string
   format: KeybindingHintFormat
 }
 
 /** Renders a single key with accessible alternative text. */
-export const Key = ({name, format}: KeyProps) => (
-  <>
-    <VisuallyHidden>{accessibleKeyName(name)}</VisuallyHidden>
-    <span aria-hidden>{format === 'condensed' ? condensedKeyName(name) : fullKeyName(name)}</span>
-  </>
-)
+export const Key = ({name, format}: KeyProps) => {
+  const isMacOS = useIsMacOS()
+
+  return (
+    <>
+      <VisuallyHidden>{accessibleKeyName(name, isMacOS)}</VisuallyHidden>
+      <span aria-hidden>{format === 'condensed' ? condensedKeyName(name, isMacOS) : fullKeyName(name, isMacOS)}</span>
+    </>
+  )
+}

packages/react/src/KeybindingHint/components/Sequence.tsx

@@ -21,5 +21,7 @@ export const Sequence = ({keys, format = 'condensed', variant = 'normal'}: Keybi
   ))
 
 /** Plain string version of `Sequence` for use in `aria` string attributes. */
-export const accessibleSequenceString = (sequence: string) =>
-  splitSequence(sequence).map(accessibleChordString).join(', then ')
+export const accessibleSequenceString = (sequence: string, isMacOS: boolean) =>
+  splitSequence(sequence)
+    .map(chord => accessibleChordString(chord, isMacOS))
+    .join(', then ')

packages/react/src/KeybindingHint/key-names.ts

@@ -1,5 +1,3 @@
-import {isMacOS} from '@primer/behaviors/utils'
-
 /** Converts the first character of the string to upper case and the remaining to lower case. */
 // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
 const capitalize = ([first, ...rest]: string) => (first?.toUpperCase() ?? '') + rest.join('').toLowerCase()
@@ -8,19 +6,16 @@ const capitalize = ([first, ...rest]: string) => (first?.toUpperCase() ?? '') +
 // would be realistically used in shortcuts. For example, the Pause/Break key is not necessary
 // because it is not found on many keyboards.
 
-// These are methods instead of plain objects to delay calling isMacOS (which depends on
-// `window.navigator`) and avoid SSR issues
-
 /**
  * Short-form iconic versions of keys. These should be intuitive (not archaic) and match icons on keyboards.
  */
-export const condensedKeyName = (key: string) =>
+export const condensedKeyName = (key: string, isMacOS: boolean) =>
   ({
-    alt: isMacOS() ? '⌥' : 'Alt', // the alt key _is_ the option key on MacOS - in the browser there is no "option" key
+    alt: isMacOS ? '⌥' : 'Alt', // the alt key _is_ the option key on MacOS - in the browser there is no "option" key
     control: '⌃',
     shift: '⇧',
-    meta: isMacOS() ? '⌘' : 'Win',
-    mod: isMacOS() ? '⌘' : '⌃',
+    meta: isMacOS ? '⌘' : 'Win',
+    mod: isMacOS ? '⌘' : '⌃',
     pageup: 'PgUp',
     pagedown: 'PgDn',
     arrowup: '↑',
@@ -44,10 +39,10 @@ export const condensedKeyName = (key: string) =>
  * Specific key displays for 'full' format. We still do show some icons (ie punctuation)
  * because that's more intuitive, but for the rest of keys we show the standard key name.
  */
-export const fullKeyName = (key: string) =>
+export const fullKeyName = (key: string, isMacOS: boolean) =>
   ({
-    alt: isMacOS() ? 'Option' : 'Alt',
-    mod: isMacOS() ? 'Command' : 'Control',
+    alt: isMacOS ? 'Option' : 'Alt',
+    mod: isMacOS ? 'Command' : 'Control',
     '+': 'Plus',
     pageup: 'Page Up',
     pagedown: 'Page Down',
@@ -64,11 +59,11 @@ export const fullKeyName = (key: string) =>
  * readers from expressing punctuation in speech, ie, reading a long pause instead of the
  * word "period".
  */
-export const accessibleKeyName = (key: string) =>
+export const accessibleKeyName = (key: string, isMacOS: boolean) =>
   ({
-    alt: isMacOS() ? 'option' : 'alt',
-    meta: isMacOS() ? 'command' : 'Windows',
-    mod: isMacOS() ? 'command' : 'control',
+    alt: isMacOS ? 'option' : 'alt',
+    meta: isMacOS ? 'command' : 'Windows',
+    mod: isMacOS ? 'command' : 'control',
     // Screen readers may not be able to pronounce concatenated words - this provides a better experience
     pageup: 'page up',
     pagedown: 'page down',

packages/react/src/__tests__/KeybindingHint.test.tsx

@@ -77,13 +77,21 @@ describe('KeybindingHint', () => {
 })
 
 describe('getAccessibleKeybindingHintString', () => {
-  it('returns full readable key names', () => expect(getAccessibleKeybindingHintString('{')).toBe('left curly brace'))
+  it('returns full readable key names', () =>
+    expect(getAccessibleKeybindingHintString('{', false)).toBe('left curly brace'))
 
-  it('joins keys in a chord with space', () => expect(getAccessibleKeybindingHintString('Command+U')).toBe('command u'))
+  it('joins keys in a chord with space', () =>
+    expect(getAccessibleKeybindingHintString('Command+U', false)).toBe('command u'))
 
   it('sorts modifiers in standard order', () =>
-    expect(getAccessibleKeybindingHintString('Alt+Shift+Command+%')).toBe('alt shift command percent'))
+    expect(getAccessibleKeybindingHintString('Alt+Shift+Command+%', false)).toBe('alt shift command percent'))
 
   it('joins chords in a sequence with "then"', () =>
-    expect(getAccessibleKeybindingHintString('Alt+9 x y')).toBe('alt 9, then x, then y'))
+    expect(getAccessibleKeybindingHintString('Alt+9 x y', false)).toBe('alt 9, then x, then y'))
+
+  it('returns "command" for "mod" on MacOS', () =>
+    expect(getAccessibleKeybindingHintString('Mod+x', true)).toBe('command x'))
+
+  it('returns "control" for "mod" on non-MacOS', () =>
+    expect(getAccessibleKeybindingHintString('Mod+x', false)).toBe('control x'))
 })

packages/react/src/hooks/index.ts

@@ -15,3 +15,4 @@ export {useMenuKeyboardNavigation} from './useMenuKeyboardNavigation'
 export {useMnemonics} from './useMnemonics'
 export {useRefObjectAsForwardedRef} from './useRefObjectAsForwardedRef'
 export {useId} from './useId'
+export {useIsMacOS} from './useIsMacOS'

packages/react/src/hooks/useIsMacOS.ts

@@ -0,0 +1,16 @@
+import {isMacOS as ssrUnsafeIsMacOS} from '@primer/behaviors/utils'
+import {useEffect, useState} from 'react'
+
+/**
+ * SSR-safe hook for determining if the current platform is MacOS. When rendering
+ * server-side, will default to non-MacOS and then re-render in an effect if the
+ * client turns out to be a MacOS device.
+ */
+export function useIsMacOS() {
+  // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+  const [isMacOS, setIsMacOS] = useState(() => (window !== undefined ? ssrUnsafeIsMacOS() : false))
+
+  useEffect(() => setIsMacOS(ssrUnsafeIsMacOS()), [])
+
+  return isMacOS
+}