JSFiddle - React, Tailwind, and code Playground

HTML

<label><input type="checkbox"/>Товар 1</label>
<label><input type="checkbox"/>Товар 2</label>
<label><input type="checkbox"/>Товар 3</label>
<label><input type="checkbox"/>Товар 4</label>
<label><input type="checkbox"/>Товар 5</label>
<label><input type="checkbox"/>Товар 6</label>
<label><input type="checkbox"/>Товар 7</label>
<label><input type="checkbox"/>Товар 8</label>
<label><input type="checkbox"/>Товар 9</label>
<label><input type="checkbox"/>Товар 10</label>
<textarea placeholder="обратная связь"></textarea>
<button>Корзина</button>

JavaScript

var $textarea = document.querySelector("textarea");
document.querySelector("button").onclick = function()
{
    var orders = [];
    [].forEach.call(document.querySelectorAll("input:checked"), function($input)
                    {
                        orders.push($input.nextSibling.textContent);
                    });
    $textarea.innerText = "Товары: " + orders.join(", ");
};