JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <input class="cb" type="checkbox"/>
</div>
<button id='add'>Add checkbox</button>
<button id='selectAll'>Select all</button>

JavaScript

$(function(){
    $('#add').click(function(){
        $('.container').append('<input class="cb" type="checkbox"/>');
    });
    $('#selectAll').click(function(){
        var checked = $('.container .cb').first().prop('checked');
        $('.container .cb').prop('checked', !checked)
    });
});