JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.11.0/jquery.validate.min.js"></script>
<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.11.0/additional-methods.js"></script>
<form id="myform">
    <input type="checkbox" name="test[]" />x
    <input type="checkbox" name="test[]" />y
    <input type="checkbox" name="test[]" />z
    <input type="submit" />
</form>
<a id="docs" href="http://docs.jquery.com/Plugins/Validation" target="_blank">Validation Documentation</a>

CSS

#docs {
    display: block;
    position: fixed;
    bottom: 0;
    right: 0;
}

JavaScript

$(document).ready(function () {

    $('#myform').validate({ // initialize the plugin
        rules: {
            'test[]': {
                required: true,
                maxlength: 2
            }
        },
        messages: {
            'test[]': {
                required: "You must check at least 1 box",
                maxlength: "Check no more than {0} boxes"
            }
        },
        submitHandler: function (form) { // for demo
            alert('valid form submitted'); // for demo
            return false; // for demo
        }
    });

});