JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<div>
    <div class="partslistbody">
        
          
                <input type="checkbox" name="parttwo" id="partoption2" value="206365-KT:" >manoji
          
            
                <select class="quantity" id="parttwoqty" name='qty2' disabled="disabled"              >
                <option value="None">0</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
                <option value="4">4</option>
                <option value="5">5</option>
                <option value="6">6</option>
                <option value="7">7</option>
                <option value="8">8</option>
                <option value="9">9</option>
                <option value="10">10</option>
                <option value="11">11</option>
                <option value="12">12</option>
                <option value="13">13</option>
                </select>
            

    </div>
</div>
    </body>
</html>

CSS

#partoption2 {
    background: none repeat scroll 0 0 #FF0000;
    height: 16px;
    position: relative;
    top: 3px;
    width: 16px;
}

JavaScript

$(document).ready(function(e) {
var $checkBox = $('#partoption2'),
    $select = $('#parttwoqty');

$checkBox.on('change',function(e){
    if ($(this).is(':checked')){
		
        $select.removeAttr('disabled');
    }else{
       $select.attr('disabled','disabled');
    }
});
 });