Subtopic
Running an online store on WordPress.
WooCommerce
Renaming, removing and reordering entries is a one-filter job. Adding a new entry is not: the filter only prints a link, and a link to an endpoint that was never registered is a 404 the filter cannot fix.
WooCommerce
The filter hands you every calculated rate for a package, which makes hiding and repricing trivial — and the result is cached against the cart contents, so a rule that depends on anything else looks random until you know why.
WooCommerce
The hook changes the main product query on the shop and archive pages, and nothing else: not shortcodes, not product blocks, not the REST API. Each of those has its own filter, and the usual complaint is a rule that works on the shop page and nowhere else.
WooCommerce
Returning false stops the product entering the cart, but it does not explain anything. The notice is a separate call, and the filter is skipped entirely when a quantity is changed on the cart page, which is the gap most validation snippets fall through.
WooCommerce
The hook belongs to the classic checkout and never fires for the checkout block. On the stores where it does fire, the common snippet writes post meta that a high-performance order store cannot see.
WooCommerce
The hook fires on every route into the completed status — admin dropdown, bulk action, REST call, automatic completion of virtual orders, and an order moved back to completed after a refund. A callback that assumes a single, first-time event is wrong on four of those.
WooCommerce
The hook fires when a gateway reports a successful payment, which is not the same as when an order is placed. Offline methods never fire it, and that is the difference between a fulfilment script that works and one that quietly skips a third of orders.
WooCommerce
A fee added here is recalculated on every cart load and never stored, which is why conditions belong inside the callback. A negative fee is a discount that bypasses coupons, and the tax on it does not always behave.
WooCommerce
The hook fires inside the cart form, which is the whole point: an input printed here is submitted with the add-to-cart request. It is also why a stray closing tag printed here breaks the button.
WooCommerce
Everything in the summary column — title, price, add-to-cart form, meta — is a callback on this one hook, each at a fixed priority. Your output lands wherever its priority says, and the add-to-cart form sits at 30.
WooCommerce
The filter changes a glyph and nothing else. The store still trades in the currency configured in settings, so a symbol swapped without a matching currency change makes the store lie about what it charges.
WooCommerce
The filter works until a payment gateway decides otherwise. Gateways carry their own button label and set it after your callback has run, which is why the wording reverts the moment a shopper picks a different method.