private static function checkout() {
		// Show non-cart errors.
		do_action( 'woocommerce_before_checkout_form_cart_notices' );

		// Check cart has contents.
		if ( WC()->cart->is_empty() && ! is_customize_preview() && apply_filters( 'woocommerce_checkout_redirect_empty_cart', true ) ) {
			return;
		}

		// Check cart contents for errors.
		do_action( 'woocommerce_check_cart_items' );

		// Calc totals.
		WC()->cart->calculate_totals();

		// Get checkout object.
		$checkout = WC()->checkout();

		if ( empty( $_POST ) && wc_notice_count( 'error' ) > 0 ) { // WPCS: input var ok, CSRF ok.

			wc_get_template( 'checkout/cart-errors.php', array( 'checkout' => $checkout ) );
			wc_clear_notices();

		} else {

			$non_js_checkout = ! empty( $_POST['woocommerce_checkout_update_totals'] ); // WPCS: input var ok, CSRF ok.

			if ( wc_notice_count( 'error' ) === 0 && $non_js_checkout ) {
				wc_add_notice( __( 'The order totals have been updated. Please confirm your order by pressing the "Place order" button at the bottom of the page.', 'woocommerce' ) );
			}

			wc_get_template( 'checkout/form-checkout.php', array( 'checkout' => $checkout ) );

		}
	}