JSFiddle - React, Tailwind, and code Playground

HTML

<select id="select">
    <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>
</select>
<textarea id="text"></textarea>

JavaScript

$('#select').change(function() {
    $('#text').attr('maxlength', $(this).val()); 
});

$('#select').change();