Copy /woocommerce/templates/content-product.php to /yourtheme/woocommerce/content-product.php and modify it as needed.
In this case, we can change the opening <li> tag from this:
<li <?php post_class(); ?>>
to this:
<li <?php post_class(); ?> id="<?php echo esc_attr( 'post-' . get_the_ID() ); ?>">
The updated content-product.php file will look like this:
<?php
/**
* The template for displaying product content within loops
*
* This template can be overridden by copying it to yourtheme/woocommerce/content-product.php.
*
* HOWEVER, on occasion WooCommerce will need to update template files and you
* (the theme developer) will need to copy the new files to your theme to
* maintain compatibility. We try to do this as little as possible, but it does
* happen. When this occurs the version of the template file will be bumped and
* the readme will list any important changes.
*
* @see https://docs.woocommerce.com/document/template-structure/
* @author WooThemes
* @package WooCommerce/Templates
* @version 3.0.0
*/
if ( ! defined( 'ABSPATH' ) ) {
exit; // Exit if accessed directly
}
global $product;
// Ensure visibility
if ( empty( $product ) || ! $product->is_visible() ) {
return;
}
?>
<li <?php post_class(); ?> id="<?php echo esc_attr( 'post-' . get_the_ID() ); ?>">
<?php
/**
* woocommerce_before_shop_loop_item hook.
*
* @hooked woocommerce_template_loop_product_link_open - 10
*/
do_action( 'woocommerce_before_shop_loop_item' );
/**
* woocommerce_before_shop_loop_item_title hook.
*
* @hooked woocommerce_show_product_loop_sale_flash - 10
* @hooked woocommerce_template_loop_product_thumbnail - 10
*/
do_action( 'woocommerce_before_shop_loop_item_title' );
/**
* woocommerce_shop_loop_item_title hook.
*
* @hooked woocommerce_template_loop_product_title - 10
*/
do_action( 'woocommerce_shop_loop_item_title' );
/**
* woocommerce_after_shop_loop_item_title hook.
*
* @hooked woocommerce_template_loop_rating - 5
* @hooked woocommerce_template_loop_price - 10
*/
do_action( 'woocommerce_after_shop_loop_item_title' );
/**
* woocommerce_after_shop_loop_item hook.
*
* @hooked woocommerce_template_loop_product_link_close - 5
* @hooked woocommerce_template_loop_add_to_cart - 10
*/
do_action( 'woocommerce_after_shop_loop_item' );
?>
</li>