JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.13.1/jquery.validate.js"></script>
<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.13.1/additional-methods.js"></script>
<form id="myform">
    <input type="text" name="firstname" class="group_input" /><br/>
    <input type="text" name="lastname" class="group_input" /><br/>
    <br/>
    <input type="submit" />
</form>

JavaScript

$(document).ready(function () {

    var names = "";
    $('.group_input').each(function() {
        names += $(this).attr('name') + " ";
    });
    names = $.trim(names);

    $.validator.addClassRules("group_input", {
        require_from_group: [1,".group_input"]
    });   
    
    $('#myform').validate({
        // other options,
        groups: {
            myGroup: names  // reference the string
        }
    });

});