JSFiddle - React, Tailwind, and code Playground

HTML

<script src="&lt;script type=&quot;text/javascript&quot; src=&quot;http://jzaefferer.github.com/jquery-validation/jquery.validate.js&quot;&gt;&lt;/script&gt;"></script>
<form name="clientdetails_form" id="clientdetails_form" method="POST" action="xxxx.php">  

<p>
<label for="state">State</label>
<select type="text" name="state" >
<option value="NY">NY</option>
<option value="DE">DE</option></select>
</p>

<p>
<label for="LicenseN"><em>*</em>License #</label>
<input id="ClientLicensenNum"  name="ClientLicensenNum" type="text" value="" >
</p>    

<input type="submit" value="submit"  >    
</form>

JavaScript

$(document).ready(function() {
    $('select').change(function() {
        var state = $(this).val();
        var license = $('#ClientLicensenNum').val();
        if (state == "DE" && license.length == 6) {
            console.log('Do something');
        }
    });
});