Gh translate button

gh-translate-button

A reusable, dependency-free language switcher. Drop it into any page; it switches UI strings, flips direction for RTL, and persists the choice only through the ?lang= URL parameter.

Requirements (non-negotiable)

• Languages (9): en, it, ar, nl, zh-CN, es, fr, de, pt-BR.
• Arabic is RTL. When ar is active, set dir="rtl" on <html>; all others are ltr.
• State lives in ?lang= only. The active language is read from and written to the URL query param. Never use localStorage/cookies — the URL is the single source of truth, so a shared link reproduces the exact language, and there's no hidden persisted state.
• No reload on switch. Update the URL with history.replaceState and re-render in place.
• Graceful fallback. Unknown/missing ?lang= → default en. Missing key in a dictionary → fall back to the en string.
• Accessible. The control is a labelled <select> (or button group) with an aria-label.

How content is marked up

Tag any translatable element with data-i18n="<key>"; the script swaps its textContent per the active language's dictionary. Set <html lang> and dir automatically.

Drop-in snippet (vanilla, no build step)

<!-- 1) Place the switcher anywhere -->
<div id="lang-switcher" aria-label="Language"></div>

<!-- 2) Mark translatable text -->
<h1 data-i18n="hero_title">We handle it</h1>
<a href="#" data-i18n="cta">Get started</a>

<!-- 3) Drop-in logic -->
<script>
(function () {
  // Supported languages. `rtl: true` only for Arabic.
  const LANGS = [
    { code: 'en',    label: 'English',    rtl: false },
    { code: 'it',    label: 'Italiano',   rtl: false },
    { code: 'ar',    label: 'العربية',     rtl: true  },
    { code: 'nl',    label: 'Nederlands', rtl: false },
    { code: 'zh-CN', label: '简体中文',     rtl: false },
    { code: 'es',    label: 'Español',    rtl: false },
    { code: 'fr',    label: 'Français',   rtl: false },
    { code: 'de',    label: 'Deutsch',    rtl: false },
    { code: 'pt-BR', label: 'Português',  rtl: false },
  ];
  const DEFAULT = 'en';

  // String table: I18N[code][key]. Fill in your real copy; en is the fallback.
  const I18N = {
    'en':    { hero_title: 'We handle it',     cta: 'Get started' },
    'it':    { hero_title: 'Lo gestiamo noi',  cta: 'Inizia' },
    'ar':    { hero_title: 'نحن نتولى الأمر',   cta: 'ابدأ الآن' },
    'nl':    { hero_title: 'Wij regelen het',  cta: 'Begin nu' },
    'zh-CN': { hero_title: '交给我们',          cta: '开始使用' },
    'es':    { hero_title: 'Nos encargamos',   cta: 'Empezar' },
    'fr':    { hero_title: 'On s’en occupe',   cta: 'Commencer' },
    'de':    { hero_title: 'Wir kümmern uns',  cta: 'Loslegen' },
    'pt-BR': { hero_title: 'A gente cuida',    cta: 'Começar' },
  };

  const known = c => LANGS.some(l => l.code === c);

  // Active language = ?lang= param, else default. No storage, ever.
  function currentLang() {
    const p = new URLSearchParams(location.search).get('lang');
    return known(p) ? p : DEFAULT;
  }

  function apply(code) {
    const lang = LANGS.find(l => l.code === code) || LANGS.find(l => l.code === DEFAULT);
    const dict = I18N[lang.code] || {};
    const fallback = I18N[DEFAULT] || {};
    document.documentElement.lang = lang.code;
    document.documentElement.dir = lang.rtl ? 'rtl' : 'ltr';
    document.querySelectorAll('[data-i18n]').forEach(el => {
      const key = el.getAttribute('data-i18n');
      const val = dict[key] != null ? dict[key] : fallback[key];
      if (val != null) el.textContent = val;
    });
  }

  function setLang(code) {
    const url = new URL(location.href);
    url.searchParams.set('lang', code);   // the ONLY place state is kept
    history.replaceState(null, '', url);  // no reload, no localStorage
    apply(code);
    render(code);
  }

  function render(active) {
    const host = document.getElementById('lang-switcher');
    if (!host) return;
    host.innerHTML = '';
    const sel = document.createElement('select');
    sel.setAttribute('aria-label', 'Select language');
    LANGS.forEach(l => {
      const opt = document.createElement('option');
      opt.value = l.code;
      opt.textContent = l.label;
      if (l.code === active) opt.selected = true;
      sel.appendChild(opt);
    });
    sel.addEventListener('change', e => setLang(e.target.value));
    host.appendChild(sel);
  }

  function init() { const c = currentLang(); apply(c); render(c); }
  window.addEventListener('popstate', init);        // back/forward keeps URL ↔ UI in sync
  if (document.readyState !== 'loading') init();
  else document.addEventListener('DOMContentLoaded', init);
})();
</script>

Adapting it

• Add a string: add the key to every I18N[code]; mark the element with data-i18n="key".
• Add a language: append to LANGS and add its I18N entry. Only ar is RTL today.
• Framework port: the same three pieces (read ?lang=, write via history.replaceState, re-render) port directly to React/Vue — keep ?lang= as the source of truth; do not introduce localStorage.
• SEO (optional): emit <link rel="alternate" hreflang="<code>" href="...?lang=<code>"> per language so each variant is discoverable.

Acceptance check

• All 9 languages selectable; switching updates text without reload.
• ?lang=ar sets dir="rtl"; others ltr.
• State is in the URL only — no localStorage/cookies anywhere.
• Unknown ?lang= and missing keys fall back to en.
• Shared link with ?lang= reproduces the exact language.