JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ivaynberg.github.io/select2/select2-3.4.6/select2.js"></script>
<link rel="stylesheet" href="http://ivaynberg.github.io/select2/select2-3.4.6/select2.css">
<link rel="stylesheet" href="//netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.css">
<select id="sel" style="width: 100%">
    <option value="1">Hello</option>
    <option value="2">Friends</option>
    <option value="3">Stackoverflow</option>
</select>
<br><br>
<button id="addok">Add OK <i class='fa fa-check'></i></button>

JavaScript

$(document).ready(function () {

    $("#sel").select2();
    
    $("#addok").click(function() {
        actual_value = $("#sel").find(':selected').text();
        
        if (actual_value.indexOf(" <i class='fa fa-check'></i>") > -1){
            alert("asd")
            return
        }
        
        newtext = actual_value + "<i class='fa fa-check'></i>";
        $("#s2id_sel").find('.select2-chosen').html(newtext);
    });
});