Displaying Hotkeys in Your Preact UI

Use formatForDisplay whenever a hotkey appears in a menu, button, tooltip, cheat sheet, or shortcut settings panel. It accepts chord strings, including physical ones such as 'Mod+[KeyS]', chord objects, parsed chords, and sequences. Store the hotkey itself, and format it when you render. A label is for reading, not for registering.

A label depends on the user's platform: Mod+S is ⌘ S on macOS and Ctrl+S elsewhere. Pick the API by where your labels render:

Format a hotkey#

import { formatForDisplay } from '@tanstack/preact-hotkeys'

formatForDisplay('Mod+S', { platform: 'mac' }) // '⌘ S'
formatForDisplay('Mod+[KeyS]', { platform: 'mac' }) // '⌘ S'
formatForDisplay({ code: 'KeyS', mod: true }, { platform: 'windows' }) // 'Ctrl+S'
formatForDisplay('Mod+[Digit2]', { platform: 'windows' }) // 'Ctrl+2'

The same label can stand for different hotkeys. Mod+S follows the character S, and Mod+[KeyS] follows the key in the S position. See Match a key's position instead. Labels for positions shorten KeyS to S and Digit2 to 2, keep readable numpad labels, and reuse punctuation and special-key symbols. Formatting doesn't change the stored hotkey or guess the user's keyboard layout.

Omit platform to detect it in the browser. On macOS, the label joins modifier symbols with spaces. Windows and Linux use names joined with +. macOS orders modifiers as Control, Option, Shift, Command, so Mod+Shift+S displays as ⇧ ⌘ S, while the hotkey itself stays Mod+Shift+S.

formatForDisplay accepts hotkeys only, including single keys such as 'Escape' and modifiers on their own such as 'Shift'. A key from a KeyboardEvent, such as a held key, can be outside the key types: pass it as { key }.

Render individual keycaps#

Set parts: true to get one label per key instead of a joined string:

const saveHotkey = 'Mod+[KeyS]'
const parts = formatForDisplay(saveHotkey, { platform: 'mac', parts: true })
// ['⌘', 'S'], one label per <kbd>

With parts omitted or false, the result is a string. A runtime boolean returns string | string[]. Parts keep literal plus keys and ignore separatorToken.

Format sequences#

Pass a sequence to format each step and join the steps with sequenceSeparator, a space by default:

formatForDisplay(['Mod+[KeyK]', 'C'], { platform: 'mac' }) // '⌘ K C'
formatForDisplay(['G', 'G'], { sequenceSeparator: ' → ' }) // 'G → G'
formatForDisplay(['Mod+[KeyK]', 'C'], { platform: 'mac', parts: true })
// [['⌘', 'K'], ['C']], one array of keycaps per step

With parts: true, a sequence returns one array per step, so you can render each step as a group of keycaps. To show the steps a user has pressed so far, see Show sequences in your UI.

Choose symbols and separators#

useSymbols accepts a boolean or separate modifiers and keys settings. Omitted fields default to true. Modifier symbols apply on macOS. Windows and Linux keep modifier names.

formatForDisplay('Shift+[ArrowUp]', {
  platform: 'mac',
  useSymbols: { modifiers: false, keys: true },
  parts: true,
}) // ['Shift', '↑']

formatForDisplay('Mod+[KeyS]', {
  platform: 'mac', useSymbols: false,
}) // 'Cmd+S'

formatForDisplay('Control++', {
  platform: 'windows', separatorToken: ' · ',
}) // 'Ctrl · +'

An empty separator joins labels directly. undefined or null uses the platform default. separatorToken applies within a chord, and sequenceSeparator applies between steps.

Supply layout labels#

A position, such as [KeyQ], gets a fallback label that may differ from the character printed on the user's keyboard. Pass an already-resolved layoutMap to label positions for a known layout:

const layoutMap = new Map([['KeyQ', 'a']])

formatForDisplay('Mod+[KeyQ]', { platform: 'mac', layoutMap }) // '⌘ A'
formatForDisplay('Mod+Q', { platform: 'mac', layoutMap }) // '⌘ Q'

Any object with get(code): string | undefined works, including a browser KeyboardLayoutMap. Formatting stays synchronous. Your app owns loading, errors, and refreshing the map: render fallback labels while it loads, then pass the resolved map on the next render. The library never requests it. Hotkeys that follow characters ignore layoutMap.

Use keyLabels for your own labels, keyed by physical code or by key name:

formatForDisplay('Mod+[KeyQ]', {
  platform: 'mac', layoutMap, keyLabels: { KeyQ: 'Action' },
}) // '⌘ Action'

keyLabels wins over a layout entry, which wins over the fallback label. Layout entries get normal letter casing and key symbols, and missing or empty entries fall back. All of these options affect display only.

The browser's KeyboardLayoutMap exists only in the browser, and it loads after the page renders. In a server-rendered app, render fallback labels first and pass the map once it loads, as above. The first render then matches the server's HTML. keyLabels works anywhere, including on the server.

Format labels in server-rendered apps#

The server doesn't know the user's platform. Without one, a label rendered on the server uses 'linux', so a Mac user gets Ctrl+S in the server's HTML. When Preact hydrates, it replaces the label's text with ⌘ S, so the label changes in front of the user. Preact doesn't update attributes during hydration, so a label in an attribute, such as a title, keeps Ctrl+S. To render the right label from the start:

1. Read the request's User-Agent header on the server, and pass detectPlatform(userAgent) as the provider's platform.
2. Format labels with useFormatForDisplay() instead of formatForDisplay.

import { HotkeysProvider, detectPlatform } from '@tanstack/preact-hotkeys'

<HotkeysProvider defaultOptions={{ platform: detectPlatform(userAgent) }}>
  <App />
</HotkeysProvider>

import { useFormatForDisplay } from '@tanstack/preact-hotkeys'

function Toolbar() {
  // Call it at the top of the component, like any hook
  const format = useFormatForDisplay()

  return (
    <ul>
      {commands.map((command) => (
        <li key={command.id}>
          {command.name} <kbd>{format(command.hotkey)}</kbd>
        </li>
      ))}
    </ul>
  )
}

useFormatForDisplay returns a function with the same options as formatForDisplay. Call the hook once at the top of the component, then call the function anywhere, including in loops and conditions. A platform passed to the function wins over the provider's.

In the browser, detectPlatform() reads the browser's own navigator, so the server and the browser get the same platform for practically every user. The provider's platform is also the default platform for hotkeys and recorders inside it. An inner provider inherits it.

Without a provider platform, useFormatForDisplay detects the platform the same way formatForDisplay does: 'linux' on the server and the user's platform in the browser. It doesn't hold the server's label until hydration finishes, so the label changes as described above. Set the provider's platform in every server-rendered Preact app.

The provider must render on the server too, so wrap your app in it where the request is available, as shown for each framework below.

Pages rendered this way depend on the request's User-Agent header. If a CDN or another shared cache stores them, it can serve one user's labels, and the platform that Mod resolves to, to other users. Keep these pages out of shared caches, or add the platform to the cache key. Vary: User-Agent also works, but it splits the cache into many small entries.

Fresh#

Each island hydrates as its own Preact app, so a provider outside the island exists only on the server. Render the provider inside the island, and pass the platform from the route. A route component receives the request as req:

// routes/index.tsx
import { detectPlatform } from '@tanstack/preact-hotkeys'
import { define } from '../utils.ts'
import Shortcuts from '../islands/Shortcuts.tsx'

export default define.page(({ req }) => {
  const platform = detectPlatform(req.headers.get('user-agent'))

  return <Shortcuts platform={platform} />
})

// islands/Shortcuts.tsx
import { HotkeysProvider } from '@tanstack/preact-hotkeys'
import type { HotkeyPlatform } from '@tanstack/preact-hotkeys'

export default function Shortcuts({ platform }: { platform: HotkeyPlatform }) {
  return (
    <HotkeysProvider defaultOptions={{ platform }}>
      <CheatSheet />
    </HotkeysProvider>
  )
}

Fresh serializes island props, so the platform reaches the browser with the page.

Astro#

Each Preact island is its own Preact app, so render the provider inside the island and pass the platform from the page. The page must render on demand to have a request: add export const prerender = false, or use output: 'server'.

---
// src/pages/index.astro
import { detectPlatform } from '@tanstack/preact-hotkeys'
import Shortcuts from '../components/Shortcuts'

export const prerender = false
const platform = detectPlatform(Astro.request.headers.get('user-agent'))
---

<Shortcuts client:load platform={platform} />

// src/components/Shortcuts.tsx
import { HotkeysProvider } from '@tanstack/preact-hotkeys'
import type { HotkeyPlatform } from '@tanstack/preact-hotkeys'

export default function Shortcuts({ platform }: { platform: HotkeyPlatform }) {
  return (
    <HotkeysProvider defaultOptions={{ platform }}>
      <CheatSheet />
    </HotkeysProvider>
  )
}

The Astro example shows this setup.

Vite server rendering#

Render your app with preact-render-to-string on the server, and pass the platform as a prop. In the browser, detectPlatform() returns the same platform, so hydrate gets the same props:

// src/App.tsx
import { HotkeysProvider } from '@tanstack/preact-hotkeys'
import type { HotkeyPlatform } from '@tanstack/preact-hotkeys'

export function App({ platform }: { platform: HotkeyPlatform }) {
  return (
    <HotkeysProvider defaultOptions={{ platform }}>
      <Toolbar />
    </HotkeysProvider>
  )
}

// src/entry-server.tsx
import { renderToString } from 'preact-render-to-string'
import { detectPlatform } from '@tanstack/preact-hotkeys'
import { App } from './App'

export function render(userAgent: string | null | undefined) {
  return renderToString(<App platform={detectPlatform(userAgent)} />)
}

// src/entry-client.tsx
import { hydrate } from 'preact'
import { detectPlatform } from '@tanstack/preact-hotkeys'
import { App } from './App'

hydrate(<App platform={detectPlatform()} />, document.getElementById('app')!)

Your server calls render with the request's User-Agent header: request.headers.get('user-agent') for a Fetch API Request, or req.headers['user-agent'] in Express.

The Vite SSR example shows this setup.

Render a label only in the browser#

To skip server rendering for a label instead, render it after hydration. In the browser, plain formatForDisplay detects the platform:

import { useEffect, useState } from 'preact/hooks'
import type { ComponentChildren } from 'preact'
import { formatForDisplay } from '@tanstack/preact-hotkeys'

function ClientOnly({ children, fallback = null }: { children: ComponentChildren; fallback?: ComponentChildren }) {
  const [hydrated, setHydrated] = useState(false)
  useEffect(() => setHydrated(true), [])
  return <>{hydrated ? children : fallback}</>
}

<ClientOnly fallback={<kbd>&nbsp;</kbd>}>
  <kbd>{formatForDisplay('Mod+S')}</kbd>
</ClientOnly>

The server and the first browser render both show the fallback, so hydration matches. On an Astro island, client:only="preact" does the same for the whole island. Fresh's IS_BROWSER is already true while an island hydrates, so use the check above for labels instead. A fallback with the label's width keeps the layout from shifting.

Static and prerendered pages#

A page rendered at build time has no request and no user, so neither formatForDisplay nor useFormatForDisplay can know the platform. This includes Astro's default static output and any page you prerender with preact-render-to-string. Render platform-specific labels in a client-only wrapper, as above.

Development warning#

In development, formatting a label on the server without a platform logs a warning once. Without a platform, the server renders 'linux' labels, so users on macOS and Windows get a different label after hydration. If you develop on Linux, you won't see the problem yourself. The warning names the missing setting. It isn't included in production builds.

Parse, compare, and store hotkeys#

parseHotkey returns each chord's key, as either a logical key or a physical code, plus its modifiers with Mod resolved. Check which one you have before reading it:

import { formatForDisplay, normalizeHotkey, parseHotkey } from '@tanstack/preact-hotkeys'

const parsed = parseHotkey('Mod+[KeyS]', 'mac')
if (parsed.code !== undefined) {
  console.log(parsed.code) // 'KeyS'; parsed.key is undefined
}
const stored = normalizeHotkey(parsed, 'mac') // 'Mod+[KeyS]'
formatForDisplay(stored, { platform: 'windows' }) // 'Ctrl+S'

A parsed chord's modifiers are already resolved for one platform. To store it as a hotkey that works on every platform, normalize it with that same platform, as above. normalizeHotkey also accepts chord strings, chord objects, and sequences. Store hotkeys, never display labels. Write a chord as a string or an object covers the forms a hotkey can take.

areHotkeysEqual(a, b) compares chords or sequences after resolving modifiers, so Mod+S equals Meta+S on macOS. Sequences compare step by step. isHotkeySequence narrows a Hotkey to a sequence, and simplifyHotkey turns a one-step sequence into its chord.

Use validateHotkey when you accept a hotkey from somewhere else, such as a settings file. It returns valid, errors, and warnings, and names the failing step of a sequence. It can't promise that the browser or operating system delivers the shortcut. To check hotkeys as users record them, see Validate and check conflicts.

Try these options together with the format toggles in the server-rendered cheat sheet example. For a full list of your app's shortcuts, see Cheat Sheet UI Helpers.