JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.10.0/jquery.validate.min.js"></script>
<form id="myform" method="POST">
    <select id="id_deals-1-sales_item" class="multi_select_mandatory" name="deals-1-sales_item" multiple="multiple">
    <option value="1">Hotel 3 Star</option>
    <option selected="selected" value="2">Hotel 4 Star</option>
    </select>
    <input type="submit"/>
</form>

JavaScript

$(document).ready(function() {
    var validator = $('#myform').validate({
          // options
          rules: {
            "deals-1-sales_item": "required",            
        },
        
        //ignore: ':hidden:not("#id_deals-1-sales_item")'                                      
    });
});