JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.10.0/jquery.validate.min.js"></script>
<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.10.0/additional-methods.js"></script>
<form id="myform">
    <input type="text" name="field1" />
    <br/>
    <input type="submit" />
</form>
<a href="http://docs.jquery.com/Plugins/Validation" target="_blank">Validation Documentation</a>

CSS

a {
    display: block;
    position: absolute;
    bottom: 0;
}

JavaScript

$(document).ready(function () {
    
    jQuery.validator.addMethod('gmail', function (value, element) {
        return this.optional(element) || /^[a-z0-9](\.?[a-z0-9]){5,}@gmail\.com$/i.test(value);
    }, "not a valid Gmail email address");
    
    $('#myform').validate({
        rules: {
            field1: {
                required: true,
                gmail: true
            }
        },
        submitHandler: function (form) { // for demo
            alert('valid form');
            return false;
        }
    });

});