Common action hooks in Wordpress - Step-by-Step Execution

Concept Flow - Common action hooks

WordPress loads core

↓

Trigger action hook

↓

Run all functions hooked

↓

Continue WordPress process

WordPress runs its core, triggers action hooks at specific points, then runs all functions attached to those hooks before continuing.

Execution Sample

Wordpress

<?php
add_action('init', 'my_init_function');
function my_init_function() {
  error_log('Init hook fired');
}
?>

This code attaches a function to the 'init' action hook that logs a message when WordPress initializes.

Execution Table

Step	Action Hook Triggered	Hooked Function	Function Output	Next Step
1	init	my_init_function	Logs 'Init hook fired' to error log	Continue loading WordPress
2	wp_head	theme_custom_head	Adds custom CSS to page header	Render page head
3	wp_footer	theme_custom_footer	Adds custom scripts before </body>	Render page footer
4	shutdown	cleanup_function	Performs cleanup tasks	End WordPress process

💡 All hooked functions run at their action points; WordPress process continues normally.

Variable Tracker

Variable	Start	After init	After wp_head	After wp_footer	After shutdown
error_log	empty	'Init hook fired'	'Init hook fired'	'Init hook fired'	'Init hook fired'
page_head	empty	empty	custom CSS added	custom CSS added	custom CSS added
page_footer	empty	empty	empty	custom scripts added	custom scripts added
cleanup_done	false	false	false	false	true

Key Moments - 2 Insights

Why does my hooked function not run if I add it after WordPress loads?

Hooks run only when WordPress triggers them during its process. Adding functions after the hook triggers means they won't run. See execution_table step 1 where 'init' runs early.

Can multiple functions run on the same action hook?

Yes, WordPress runs all functions hooked to an action in the order they were added. The execution_table shows different hooks but multiple functions can attach to one hook.

Visual Quiz - 3 Questions

Look at the execution_table, what output does 'my_init_function' produce at step 1?

A Adds custom scripts before </body>

B Adds custom CSS to page header

C Logs 'Init hook fired' to error log

D Performs cleanup tasks

💡 Hint

Check the 'Function Output' column for step 1 in execution_table.

At which step does WordPress add custom scripts before the closing body tag?

A init

B wp_footer

C wp_head

D shutdown

💡 Hint

Look at the 'Action Hook Triggered' and 'Function Output' columns in execution_table.

If you add a function to 'shutdown' hook, when will it run?

A At the very end of WordPress process

B During page header rendering

C Before WordPress loads core

D Immediately after 'init' hook

💡 Hint

Refer to the last row in execution_table and variable_tracker for 'cleanup_done'.

Concept Snapshot

WordPress action hooks let you run your code at specific points.
Use add_action('hook_name', 'your_function') to attach.
WordPress triggers hooks during loading, rendering, and shutdown.
All hooked functions run in order when the hook fires.
Hooks help customize behavior without changing core files.

Full Transcript

WordPress uses action hooks to let developers add custom code at key points. When WordPress loads, it triggers hooks like 'init', 'wp_head', 'wp_footer', and 'shutdown'. Functions attached to these hooks run automatically. For example, a function hooked to 'init' runs early to set up things. Multiple functions can attach to the same hook and run in order. Hooks run only when WordPress triggers them, so adding functions too late means they won't run. This system helps customize WordPress safely and flexibly.