JSFiddle - React, Tailwind, and code Playground

HTML

<div id="input_one">
    <input type="checkbox" checked value="one" />
    <input type="checkbox" checked value="one_1" />
    <input type="checkbox" value="one_2" />
    <input type="checkbox" checked value="one_3" />
    <input type="checkbox" checked value="one_4" />
</div>
<div id="input_two">
    <input type="checkbox" value="two_1" />
    <input type="checkbox" checked value="two_2" />
    <input type="checkbox" checked value="two_3" />
    <input type="checkbox" checked value="two_4" />
    <input type="checkbox" checked value="two_5" />
</div>
<div id="t_area">
    <textarea id="get_checked"></textarea>
</div>

JavaScript

function updateTextArea() {
    var allVals = [];
    $('#input_one :checked,#input_two :checked').each(function () {
        allVals.push($(this).val());
    });
    $('#get_checked').val(allVals);
}
$(function () {
    $('#input_one input,#input_two input').click(updateTextArea);
});