JSFiddle - React, Tailwind, and code Playground

HTML

<select id="rootNodes">
    <option value="238">Japan</option>
    <option value="159">France</option>  
    <option value="199">Germany</option>  
</select>

JavaScript

var rootID;
var assetBuilderURL = 'http://www.mysite.com/builder?id=';

$('#rootNodes').change(function() {
    
    rootID = $(this).val();
    alert(assetBuilderURL+rootID);
    
});