Removing hooks in Wordpress - Step-by-Step Execution

Concept Flow - Removing hooks

Add Hook with add_action()

↓

Hook Registered in WordPress

↓

Remove Hook with remove_action()

↓

Hook Unregistered

↓

Hook Callback No Longer Runs

This flow shows how a hook is first added, then removed, so its callback stops running.

Execution Sample

Wordpress

<?php
function say_hello() {
  echo 'Hello!';
}
add_action('init', 'say_hello');
remove_action('init', 'say_hello');
?>

This code adds a hook to run say_hello on 'init', then removes it so it won't run.

Execution Table

Step	Action	Hook List State	Callback Called	Output
1	add_action('init', 'say_hello')	init: [say_hello]	No
2	WordPress fires 'init' hook	init: [say_hello]	Yes	Hello!
3	remove_action('init', 'say_hello')	init: []	No
4	WordPress fires 'init' hook again	init: []	No

💡 After remove_action, 'say_hello' is no longer in 'init' hook list, so callback does not run.

Variable Tracker

Variable	Start	After Step 1	After Step 3	Final
hook_list['init']	[]	[say_hello]	[]	[]

Key Moments - 2 Insights

Why does the callback still run if remove_action is called after add_action?

Because WordPress fires the 'init' hook before remove_action is called (see Step 2). The callback runs when the hook fires, so removing it afterward stops future runs only.

What happens if the callback name or priority differs in remove_action?

The callback won't be removed because remove_action must match the exact callback and priority used in add_action (not shown in table but important).

Visual Quiz - 3 Questions

Look at the execution table, what is the state of 'init' hook list after Step 3?

A ['say_hello', 'another_callback']

B ['say_hello']

C []

D null

💡 Hint

Check the 'Hook List State' column at Step 3.

At which step does the callback 'say_hello' run?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Callback Called' and 'Output' columns.

If remove_action was called before add_action, what would happen?

A Callback would run once

B Callback would never run

C Callback would run twice

D Error occurs

💡 Hint

Think about the hook list state before and after add_action.

Concept Snapshot

add_action('hook', 'callback') adds a callback to a hook
remove_action('hook', 'callback') removes it
Callbacks run only if still registered when hook fires
Order matters: remove_action after hook fires stops future runs
Callback and priority must match exactly to remove

Full Transcript

This visual shows how WordPress hooks work when adding and removing callbacks. First, add_action registers a callback to a hook. When WordPress fires that hook, the callback runs. If remove_action is called after the hook fires, it removes the callback so it won't run next time. The hook list changes from having the callback to empty after removal. The callback runs only when the hook fires and the callback is registered. Matching callback names and priorities are required to remove hooks correctly.