function auto_add_to_cart(btn, product_id) {
    $(btn).attr('disabled', 'disabled');

    var data = {
        action: 'woocommerce_ajax_add_to_cart',
        product_id: product_id,
        product_sku: '',
        quantity: 1,
        variation_id: 0,
    };

    $.ajax({
        type: 'post',
        url: wc_add_to_cart_params.ajax_url,
        data: data,
        success: function(response) {
            if (response.checkout_url != '' && response.checkout_url !== undefined) {
                $(btn).removeAttr('disabled');
                window.location = response.checkout_url;
            }
        },
    });

}