JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.0/jquery.min.js"></script>
<div id="checkout">
    <p>Checkout Options:</p>
    <label for="register">
        <input type="radio" name="account" value="register" id="register" checked>
        <b>Register Account</b></label>
    <br>
    <label for="guest">
        <input type="radio" name="account" value="guest" id="guest">
        <b>Guest Checkout</b>
    </label>
</div>

JavaScript

var selected = $("#checkout").find("input[name='account']");
    selected.change(function(){
        alert($(this).val());
    });