JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
<script src="http://js.nicdn.de/bootstrap/formhelpers/docs/assets/js/bootstrap-formhelpers-countries.en_US.js"></script>
<script src="http://js.nicdn.de/bootstrap/formhelpers/docs/assets/js/bootstrap-formhelpers-countries.js"></script>
<script src="http://js.nicdn.de/bootstrap/formhelpers/docs/assets/js/bootstrap-formhelpers-states.en_US.js"></script>
<script src="http://js.nicdn.de/bootstrap/formhelpers/docs/assets/js/bootstrap-formhelpers-states.js"></script>
<link rel="stylesheet" href="http://js.nicdn.de/bootstrap/formhelpers/docs/assets/css/bootstrap-formhelpers.css">
    
<form>
    <label>Country *</label>
    <select id="countries" class="form-control bfh-countries"></select>
    <label>State</label>
    <select id="states" class="form-control bfh-states" data-country="countries"></select>
</form>
<br>
<button onclick="test()" class="btn">Load Country</button>

JavaScript

function test(){
    var select = document.getElementById('countries')
    , event = document.createEvent("UIEvents");
    select.value = "AU";
    event.initUIEvent("change", true, true);
    select.dispatchEvent(event);
}