JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/select2/4.0.0/css/select2.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/select2/4.0.0/js/select2.min.js"></script>
<select class="js-example-data-array">
</select>

JavaScript

var data = [{
    id: 'all',
    text: 'All',
    children: [{
        id: 'item1',
        text: 'item1'
    }, {
        id: 'item2',
        text: 'item2'
    }]
}];

$('.js-example-data-array').select2({data:data});

$('.js-example-data-array').select2('val',['item1']);