WooCommerce 新增「立即結帳」按鈕

/**
 * 立刻結帳按鈕 buy now
 * 
 * @link https://stackoverflow.com/a/64088471/6784662
 *
 * @return void
 */
/* Create Buy Now Button dynamically after Add To Cart button */
function add_content_after_addtocart() {
    
    // get the current post/product ID
    $current_product_id = get_the_ID();

    // get the product based on the ID
    $product = wc_get_product( $current_product_id );

    // get the "Checkout Page" URL
    $checkout_url = WC()->cart->get_checkout_url();

    // run only on simple products
    if( $product->is_type( 'simple' ) ){
        echo '<a href="'.$checkout_url.'?add-to-cart='.$current_product_id.'" class="buy-now button">立刻結帳</a>';
    }
}
add_action( 'woocommerce_after_add_to_cart_button', 'add_content_after_addtocart' );