Add to cart function

(function() {
    var productID = "33392502014038";
    var URL = 'https://www.trihard.co/cart/add.js';
    var formData = new FormData;
    formData.append("form_type", "product");
    formData.append("utf8", "%E2%9C%93");
    formData.append("id", productID);
    formData.append("quantity", "1");
    formData.append("purchase_type", "onetime");
    var xhr = new XMLHttpRequest();
    xhr.withCredentials = true;
    xhr.addEventListener('readystatechange', function () {
        if (this.readyState === 4) {
            window.location.reload();
        }
    });
    xhr.open('POST', URL);
    xhr.setRequestHeader('cache-control', 'no-cache');
    xhr.send(formData);
})();