JSFiddle - React, Tailwind, and code Playground

HTML

<form name="f1">
   <input type="checkbox" name="others" id="chk" > Others
   <select id="that_select" disabled>
     <option value="a">A</option>
     <option value="b" selected>B</option>
     <option value="c">C</option>
   </select>
</form>

JavaScript

$('#chk').change(function(){ 
    if($('#chk').is(':checked')){
        $('#that_select').removeAttr('disabled');
    }
    else{
        $('#that_select').attr('disabled','disabled');
    }
});