# LanguageSwitcher

> Compact language selector: a current-language trigger that fans out the other locales as a button group.

- Status: stable
- Group: navigation
- Page: https://www.digitaltableteur.com/design-system/components/language-switcher
- Contract: https://www.digitaltableteur.com/contracts/v1/LanguageSwitcher.contract.json

## When to use

LanguageSwitcher is the site-chrome locale control: the current language shows as a compact button that fans out a tray of the other locales on demand. It is controlled; update your i18n instance in `onLanguageChange` and pass the new `currentLang` back. Each option's `ariaLabel` is the language's own name ("Suomi"), not an action phrase: the trigger and every option are named "<label>, <name>", and options carry `lang` so screen readers pronounce the name in that language. The closed tray is `inert` so hidden options can never take focus. Escape or an outside click closes it; tabbing out of the open tray does not.

## When not to use

- Do not use flags as the only label; flags name countries, not languages.

## Look-alikes

The contract names no look-alike with a deciding condition.

## Props

| Prop | Type | Default | Description | Required |
| --- | --- | --- | --- | --- |
| `languages` | `LanguageSwitcherOption[]` | none | Available languages: code (also set as lang), visible label and ariaLabel, the language's own name used in the "<label>, <name>" accessible name. | Yes |
| `currentLang` | `string` | none | Currently selected language code. | Yes |
| `onLanguageChange` | `(code: string) => void` | none | Called with the selected language code. | Yes |
| `className` | `string` | none | Optional classes on the group wrapper. | No |
| `buttonClassName` | `string` | shrink-0 whitespace-nowrap px-2.5 py-1.5 text-sm font-heading font-semibold uppercase tracking-widest transition-colors motion-reduce:transition-none cursor-pointer rounded-sm border border-transparent bg-transparent text-muted-foreground hover:text-foreground hover:bg-foreground/5 | Base class override applied to every language button. | No |
| `activeButtonClassName` | `string` | text-foreground hover:text-foreground | Class override for the current-language trigger. | No |
| `openTriggerClassName` | `string` | bg-foreground/5 border-foreground text-foreground hover:border-foreground | Class override for the trigger while the tray is open. | No |
| `floatedButtonClassName` | `string` | font-semibold text-foreground/80 hover:text-foreground | Class override for the fanned-out tray options. | No |

## Variants

No variant dimensions and no props with a fixed set of values.

## Invalid combinations

The contract records no invalid combinations.

## Keyboard

| Key | Behaviour |
| --- | --- |
| Tab | Moves focus to the control and on to the next focusable element. (standard) |
| Enter | Activates the focused control. (standard) |
| Space | Activates or toggles the focused control. (standard) |
| Escape | Closes or dismisses the open layer. (standard) |

Rows marked (standard) name a key the contract lists without a description; the behaviour shown is the usual one for that key.

## Rules

Every item under When not to use is a MUST NOT. MUST and SHOULD follow RFC 2119.

| Level | Rule | How it is checked |
| --- | --- | --- |
| MUST | ARIA: Role=group with aria-label. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Trigger aria-expanded + aria-controls. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Each option is named '<label>, <language name>' (visible label first, WCAG 2.5.3) and carries lang. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | Required stories produce no axe violations at the configured severity. | Automated by `npm run test:stories:matrix:ci`. WCAG 2.5.8. |
| MUST | The accessibility tree (role, name, state) matches the committed snapshot for every required story. | Automated by `npm run test:stories:matrix:ci`. WCAG 1.3.1, 4.1.2. |
| MUST | The component remains legible and operable under a real browser forced-colors: active pass. | Automated by `npm run test:stories:hc`. |
| MUST | Every documented keyboard interaction works as specified. | Not yet verified: no evidence record. WCAG 2.1.1, 2.1.2. |
| MUST | A human completed an end-to-end accessibility review of this component. | Manual review, last on 2026-11-04. |
| SHOULD | Write each option's ariaLabel as the language's own name ("Suomi", "Svenska"), not an action phrase; the component builds the "<label>, <name>" accessible name from it. | Not stated in the contract. |
| SHOULD | Keep it controlled: change the i18n language inside onLanguageChange and feed the new currentLang back down. | Not stated in the contract. |
| SHOULD | Use short locale labels (EN/FI/SV); the fan tray is chrome, not a settings page. | Not stated in the contract. |
| SHOULD | Trust the built-in Escape, outside-click close, and inert tray; do not wrap it in another disclosure. | Not stated in the contract. |
| SHOULD NOT | Do not bury language choice in a settings modal on public pages; it is a first-visit need and belongs in the header. | Not stated in the contract. |

## Install and import

- Install: `npm install @digitaltableteur/react` (version 0.9.1, restricted access on npm).
- Import: `import { LanguageSwitcher } from "@digitaltableteur/react";`
- Entry point: `@digitaltableteur/react/navigation` exports it too.
- Styles: import `@digitaltableteur/react/style.css` once at the app boundary.
- Also available as the custom element `<dt-language-switcher>`; see the custom elements manifest.

## Links

- Machine-readable contract (Design System Contract 1.0): https://www.digitaltableteur.com/contracts/v1/LanguageSwitcher.contract.json
- Markdown version of this page: https://www.digitaltableteur.com/design-system/components/language-switcher.md
- Component index as JSON: https://www.digitaltableteur.com/design-system/components.json
- All components: https://www.digitaltableteur.com/design-system/components
- Source: The implementation lives in a private repository. This page, its Markdown twin and the contract are generated from it at build time and are the public source of truth.