Cambiar idioma con JS

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select id="idioma">
  <option value="es">Español</option>
  <option value="en">Ingles</option>
  <option value="pt">Portugues</option>
</select>

<div id="multi-lang-field-id">
<br/>
</div>

JavaScript

var lista = document.getElementById("idioma");
var idioma = localStorage.getItem("idioma");

var contents = {
  en: "Hello",
  es: "Hola",
  pt: "Ola"
};

if (idioma) {

  lista.value = idioma;
  document.getElementById("multi-lang-field-id").innerHTML = contents[idioma];
} else {
  document.getElementById("multi-lang-field-id").innerHTML = contents[lista.value];
}

var _lang = $("#idioma").val();

$("select").on("change", function() {
  cambiaId();
  location.reload();
});

function cambiaId() {
  _lang = $("#idioma").val();
  //alert(_lang);
  localStorage.setItem("idioma", _lang)

}