gengns/index.html

## readme.txt
If you want to test it locally:
chromium-browser --allow-file-access-from-files

## index.html
<!DOCTYPE html>
<head>
  <meta charset="UTF-8">
</head>
<body>
  <label class="T">Usuario</label>
  <label class="T">Contraseña</label>
  <select>
    <option value="es">Español</option>
    <option value="en">English</option>
    <option value="fr">Français</option>
  </select>
  <script src="https://unpkg.com/axios/dist/axios.min.js"></script>
  <script src="index.js"></script>
</body>
</html>

## index.js
// Translator
let T_ = txt => txt

// Default language
if (!localStorage.lang)  localStorage.lang = navigator.language.slice(0, 2)

// Default selection
if (localStorage.lang != 'es') {
  document.querySelector('select').value = localStorage.lang
  language_update(localStorage.lang)
}

// Changes selection
document.querySelector('select').onchange = e => {
  localStorage.lang = e.target.value
  location.reload()
}

// Loads file and updates translation
function language_update(lang) {
  axios.get(`language.${lang}.json`)
  .then(r => {
    // If there is not translation, we will return the current text
    T_ = txt => r.data && r.data[txt] ? r.data[txt] : txt

    // Translates all text content with T class
    document.querySelectorAll('.T')
      .forEach(e => e.textContent = T_(e.textContent))
  })
}

## language.en.json
{
  "Usuario": "User",
  "Contraseña": "Password"
}

## language.fr.json
{
  "Usuario": "Utilisateur",
  "Contraseña": "Mot de passe"
}
	If you want to test it locally:
	chromium-browser --allow-file-access-from-files
	<!DOCTYPE html>
	<head>
	<meta charset="UTF-8">
	</head>
	<body>
	<label class="T">Usuario</label>
	<label class="T">Contraseña</label>
	<select>
	<option value="es">Español</option>
	<option value="en">English</option>
	<option value="fr">Français</option>
	</select>
	<script src="https://unpkg.com/axios/dist/axios.min.js"></script>
	<script src="index.js"></script>
	</body>
	</html>
	// Translator
	let T_ = txt => txt

	// Default language
	if (!localStorage.lang) localStorage.lang = navigator.language.slice(0, 2)

	// Default selection
	if (localStorage.lang != 'es') {
	document.querySelector('select').value = localStorage.lang
	language_update(localStorage.lang)
	}

	// Changes selection
	document.querySelector('select').onchange = e => {
	localStorage.lang = e.target.value
	location.reload()
	}

	// Loads file and updates translation
	function language_update(lang) {
	axios.get(`language.${lang}.json`)
	.then(r => {
	// If there is not translation, we will return the current text
	T_ = txt => r.data && r.data[txt] ? r.data[txt] : txt

	// Translates all text content with T class
	document.querySelectorAll('.T')
	.forEach(e => e.textContent = T_(e.textContent))
	})
	}