JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<select multiple>
 <option value="1" selected>1</option>
 <option value="2" selected>2</option>
 <option value="3">3</option>
</select>

JavaScript

var a = [];

var language = $("select").val();
console.log("language: "+language);
a = language.toString().split(",");

console.log("language: "+language);     
console.log("Languages : " + $.param({"language": a}, true));