JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://jqueryvalidation.org/files/dist/jquery.validate.min.js"></script>
<form method="POST" id="TestForm">
    <input name="txtIn" type="text" id="txtIn"><span class="add"></span>

    <p></p>
    <button id="submit">Submit</button>
</form>

CSS

label.error:after {
    content:"";
    display: inline-block;
    margin-left:10px;
    background: url("http://dummyimage.com/15x15/de1417/de1417.png") no-repeat;
    width: 15px;
    height: 15px;
}
.validicon {
    display: inline-block;
    margin-left:10px;
    background-color: blue;
    width: 15px;
    height: 15px;
}

JavaScript

if ($('#TestForm input').hasClass('valid')) {
    $('.add').addClass('validicon');
} else {
    $('.add').removeClass('validicon');
}

$('#TestForm').validate({
    rules: {
        txtIn: {
            required: true,
            rangelength: [8, 16]
        }
    },
    messages: {
        txtIn: {
            required: "Please enter something",
            rangelength: "Icon"
        },

    }

});