JSFiddle - React, Tailwind, and code Playground

HTML

<select id='position'>
    <option>Choose..</option>
    <option value="1">Formative</option>
    <option value="2">Submative</option>
</select>
<select id='second'>
    <option value="1">First</option>
    <option value="2">Something else</option>
</select>

JavaScript

$(document).ready(function() {

    $('#my_sel').change(function(){
        if($(this).val() === '1'){
            $('#second').attr('disabled', 'disabled');
        }else{
            $('#second').attr('disabled', false);
        }
    });

});