JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />

JavaScript

$('input[type=checkbox]').on('change', function () {
    var total = $('input[type=checkbox]:checked').length;
    alert(total);
});