Displaying Hotkeys in Your Ember 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/ember-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 app boots. In a FastBoot app, render fallback labels first and pass the map once it loads, as above. keyLabels works anywhere, including in FastBoot.

Format labels in server-rendered apps#

The server doesn't know the user's platform. Without one, a label rendered in FastBoot uses 'linux', so a Mac user gets Ctrl+S in the server's HTML and ⌘ S once the app boots in the browser. To render the right label from the start:

1. Read the request's User-Agent header from the fastboot service, and pass detectPlatform(userAgent) as the platform of a createHotkeysScope scope.
2. Format labels with useFormatForDisplay(scope) instead of formatForDisplay.

Create the scope in a component near the top of your app, such as the one your application template renders:

// app/components/app-shell.gts
import Component from '@glimmer/component'
import { service } from '@ember/service'
import { createHotkeysScope, detectPlatform } from '@tanstack/ember-hotkeys'
import Toolbar from './toolbar'

// ember-cli-fastboot doesn't ship types, so declare the part you use
interface FastBootService {
  request: { headers: { get(name: string): string | null } } | null
}

export default class AppShell extends Component {
  @service declare fastboot: FastBootService

  hotkeys = createHotkeysScope({
    platform: detectPlatform(
      this.fastboot.request?.headers.get('user-agent'),
    ),
  })

  <template>
    <Toolbar @hotkeys={{this.hotkeys}} />
  </template>
}

// app/components/toolbar.gts
import Component from '@glimmer/component'
import { useFormatForDisplay } from '@tanstack/ember-hotkeys'
import type { EmberHotkeysScope, Hotkey } from '@tanstack/ember-hotkeys'

const commands: Array<{ name: string; hotkey: Hotkey }> = [
  { name: 'Save', hotkey: 'Mod+S' },
  { name: 'Search', hotkey: 'Mod+K' },
]

interface ToolbarSignature {
  Args: { hotkeys: EmberHotkeysScope }
}

export default class Toolbar extends Component<ToolbarSignature> {
  format = useFormatForDisplay(this.args.hotkeys)

  <template>
    <ul>
      {{#each commands as |command|}}
        <li>{{command.name}} <kbd>{{this.format command.hotkey}}</kbd></li>
      {{/each}}
    </ul>
  </template>
}

useFormatForDisplay returns a function with the same options as formatForDisplay, and templates can call it as a helper. It reads the scope's platform each time it formats, so labels update when the scope's defaults change. A platform passed to the function wins over the scope's. Without a scope, it works like formatForDisplay.

In the browser, fastboot.request is null, so detectPlatform() reads the browser's navigator. The server and the browser get the same platform for practically every user. The scope's platform is also the default platform for the hotkeys and recorders that use the scope. Pass the scope to child components, such as @hotkeys={{this.hotkeys}}, so their labels use the same platform.

Without a scope platform, useFormatForDisplay renders 'linux' labels in FastBoot. By default, the app replaces the server's HTML when it boots in the browser, so the labels then switch to the browser's platform. Mac users see Ctrl+S until the app boots. Set the scope's platform to avoid that.

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.

Render a label only in the browser#

To leave a label out of the server's HTML instead, check the fastboot service's isFastBoot. In the browser, plain formatForDisplay detects the platform:

import Component from '@glimmer/component'
import { service } from '@ember/service'
import { formatForDisplay } from '@tanstack/ember-hotkeys'

interface FastBootService {
  isFastBoot: boolean
}

export default class SaveShortcut extends Component {
  @service declare fastboot: FastBootService

  <template>
    {{#if this.fastboot.isFastBoot}}
      <kbd>&nbsp;</kbd>
    {{else}}
      <kbd>{{formatForDisplay 'Mod+S'}}</kbd>
    {{/if}}
  </template>
}

isFastBoot is true only while the app renders in FastBoot. A placeholder with the label's width keeps the layout from shifting.

Static and prerendered pages#

Prember renders pages with FastBoot at build time. A page rendered at build time has no request and no user, so neither formatForDisplay nor useFormatForDisplay can know the platform. The scope recipe above gets 'linux' there, because the build sends no User-Agent header. Render platform-specific labels only in the browser, as above. useFormatForDisplay without a scope platform also works: it shows 'linux' labels until the app boots, then switches.

Development warning#

In development, formatting a label in FastBoot without a platform logs a warning once. Without a platform, FastBoot renders 'linux' labels, so users on macOS and Windows get a different label once the app boots. If you develop on Linux, you won't see the problem yourself. The warning 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/ember-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.

For a full list of your app's shortcuts, see Cheat Sheet UI Helpers.