Can't you use css instead of javascript to toggle the show/hide?
E.g.:
.lang_fr,.lang_en,.lang_es {display:none}
.fr .lang_fr {display:inline}
.en .lang_en {display:inline}
.es .lang_es {display:inline}
...
<div class="fr">
<input type="text" name="name_fr" value="Bonjour" class="i18n lang_fr">
<input type="text" name="name_en" value="Hello" class="i18n lang_en">
<input type="text" name="name_es" value="Hola" class="i18n lang_es">
</div>
Then just toggle the fr
class of the outer div.