JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.11.1/jquery.validate.min.js"></script>
<form id="myform">
    <select name="myselect">
        <option value="">select...</option>
        <option value="foo">foo</option>
        <option value="bar">bar</option>
    </select>
    <br/>
    <input type="submit" />
</form>

JavaScript

$(document).ready(function () {

    $.validator.setDefaults({
        rules: {
            myselect: {
                required: true
            }
        }
    });

    $('#myform').validate({
        // submitHandler for demo
        submitHandler: function (form) {
            alert('valid form');
            return false;
        }
    });

});