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add_action( string $hook_name, callable $callback, int $priority = 10, int $accepted_args = 1 ): true

Adds a callback function to an action hook.

Description

Actions are the hooks that the WordPress core launches at specific points during execution, or when specific events occur. Plugins can specify that one or more of its PHP functions are executed at these points, using the Action API.

Parameters

$hook_name string Required
The name of the action to add the callback to.
$callback callable Required
The callback to be run when the action is called.
$priority int Optional
Used to specify the order in which the functions associated with a particular action are executed.
Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action.

Default: 10

$accepted_args int Optional
The number of arguments the function accepts.

Default: 1

Return

true Always returns true.

More Information

Usage

add_action( $hook, $function_to_add, $priority, $accepted_args );

To find out the number and name of arguments for an action, simply search the code base for the matching do_action() call. For example, if you are hooking into ‘save_post’, you would find it in post.php:

do_action( 'save_post', $post_ID, $post, $update );

Your add_action call would look like:

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

And your function would be:

function wpdocs_my_save_post( $post_ID, $post, $update ) {
   // do stuff here
}

Source

File: wp-includes/plugin.php. View all references

function add_action( $hook_name, $callback, $priority = 10, $accepted_args = 1 ) {
	return add_filter( $hook_name, $callback, $priority, $accepted_args );
}

Uses

Uses Description
add_filter() wp-includes/plugin.php

Adds a callback function to a filter hook.

Used By

Used By Description
wp_enqueue_block_support_styles() wp-includes/script-loader.php

Hooks inline styles in the proper place, depending on the active theme.
_wp_theme_json_webfonts_handler() wp-includes/script-loader.php

Runs the theme.json webfonts handler.
wp_enqueue_block_style() wp-includes/script-loader.php

Enqueues a stylesheet for a specific block.
locate_block_template() wp-includes/block-template.php

Finds a block template with equal or higher specificity than a given PHP template file.
WP_Sitemaps::init() wp-includes/sitemaps/class-wp-sitemaps.php

Initiates all sitemap functionality.
WP_Recovery_Mode::initialize() wp-includes/class-wp-recovery-mode.php

Initialize recovery mode for the current request.
WP_Site_Health::__construct() wp-admin/includes/class-wp-site-health.php

WP_Site_Health constructor.
wp_is_site_initialized() wp-includes/ms-site.php

Checks whether a site is initialized.
register_and_do_post_meta_boxes() wp-admin/includes/meta-boxes.php

Registers the default post meta boxes, and runs the do_meta_boxes actions.
WP_Privacy_Policy_Content::text_change_check() wp-admin/includes/class-wp-privacy-policy-content.php

Quick check if any privacy info has changed.
WP_Roles::get_roles_data() wp-includes/class-wp-roles.php

Gets the available roles data.
WP_Widget_Text::_register_one() wp-includes/widgets/class-wp-widget-text.php

Add hooks for enqueueing assets when registering all widget instances of this widget class.
WP_Widget_Custom_HTML::_register_one() wp-includes/widgets/class-wp-widget-custom-html.php

Add hooks for enqueueing assets when registering all widget instances of this widget class.
WP_Widget_Media::_register_one() wp-includes/widgets/class-wp-widget-media.php

Add hooks while registering all widget instances of this widget class.
_WP_Editors::enqueue_default_editor() wp-includes/class-wp-editor.php

Enqueue all editor scripts.
_wp_delete_customize_changeset_dependent_auto_drafts() wp-includes/nav-menu.php

Deletes auto-draft posts associated with the supplied changeset.
WP_Customize_Manager::import_theme_starter_content() wp-includes/class-wp-customize-manager.php

Imports theme starter content into the customized state.
WP_Post_Type::register_meta_boxes() wp-includes/class-wp-post-type.php

Registers the post type meta box if a custom callback was specified.
WP_Post_Type::add_hooks() wp-includes/class-wp-post-type.php

Adds the future post hook action for the post type.
WP_Customize_Widgets::selective_refresh_init() wp-includes/class-wp-customize-widgets.php

Adds hooks for selective refresh.
WP_Customize_Selective_Refresh::init_preview() wp-includes/customize/class-wp-customize-selective-refresh.php

Initializes the Customizer preview.
WP_Customize_Selective_Refresh::enqueue_preview_scripts() wp-includes/customize/class-wp-customize-selective-refresh.php

Enqueues preview scripts.
WP_Customize_Selective_Refresh::__construct() wp-includes/customize/class-wp-customize-selective-refresh.php

Plugin bootstrap for Partial Refresh functionality.
rest_api_default_filters() wp-includes/rest-api.php

Registers the default REST API filters.
WP_Customize_Setting::aggregate_multidimensional() wp-includes/class-wp-customize-setting.php

Set up the setting for aggregated multidimensional values.
wp_admin_bar_customize_menu() wp-includes/admin-bar.php

Adds the “Customize” link to the Toolbar.
WP_Widget_Factory::__construct() wp-includes/class-wp-widget-factory.php

PHP5 constructor.
WP_Customize_Site_Icon_Control::__construct() wp-includes/customize/class-wp-customize-site-icon-control.php

Constructor.
WP_Customize_Nav_Menu_Item_Setting::__construct() wp-includes/customize/class-wp-customize-nav-menu-item-setting.php

Constructor.
WP_Customize_Nav_Menus::customize_preview_init() wp-includes/class-wp-customize-nav-menus.php

Adds hooks for the Customizer preview.
WP_Customize_Nav_Menus::__construct() wp-includes/class-wp-customize-nav-menus.php

Constructor.
WP_Site_Icon::__construct() wp-admin/includes/class-wp-site-icon.php

Registers actions and filters.
login_header() wp-login.php

Output the login page header.
Language_Pack_Upgrader::bulk_upgrade() wp-admin/includes/class-language-pack-upgrader.php

Bulk upgrade language packs.
Theme_Upgrader::install() wp-admin/includes/class-theme-upgrader.php

Install a theme package.
Theme_Upgrader::upgrade() wp-admin/includes/class-theme-upgrader.php

Upgrade a theme.
Plugin_Upgrader::install() wp-admin/includes/class-plugin-upgrader.php

Install a plugin package.
Plugin_Upgrader::upgrade() wp-admin/includes/class-plugin-upgrader.php

Upgrade a plugin.
WP_List_Table::__construct() wp-admin/includes/class-wp-list-table.php

Constructor.
WP_Theme_Install_List_Table::prepare_items() wp-admin/includes/class-wp-theme-install-list-table.php
wp_plugin_update_rows() wp-admin/includes/update.php

Adds a callback to display update information for plugins with updates available.
wp_theme_update_rows() wp-admin/includes/update.php

Adds a callback to display update information for themes with updates available.
uninstall_plugin() wp-admin/includes/plugin.php

Uninstalls a single plugin.
add_menu_page() wp-admin/includes/plugin.php

Adds a top-level menu page.
add_submenu_page() wp-admin/includes/plugin.php

Adds a submenu page.
WP_Plugin_Install_List_Table::prepare_items() wp-admin/includes/class-wp-plugin-install-list-table.php
WP_Internal_Pointers::enqueue_scripts() wp-admin/includes/class-wp-internal-pointers.php

Initializes the new feature pointers.
Custom_Image_Header::__construct() wp-admin/includes/class-custom-image-header.php

Constructor – Register administration header callback.
Custom_Image_Header::init() wp-admin/includes/class-custom-image-header.php

Set up the hooks for the Custom Header admin page.
Custom_Background::__construct() wp-admin/includes/class-custom-background.php

Constructor – Registers administration header callback.
Custom_Background::init() wp-admin/includes/class-custom-background.php

Sets up the hooks for the Custom Background admin page.
WP_Customize_Manager::customize_preview_init() wp-includes/class-wp-customize-manager.php

Prints JavaScript settings.
WP_Customize_Manager::setup_theme() wp-includes/class-wp-customize-manager.php

Starts preview and customize theme.
WP_Customize_Manager::__construct() wp-includes/class-wp-customize-manager.php

Constructor.
wp_cron() wp-includes/cron.php

Register _wp_cron() to run on the {@see ‘wp_loaded’} action.
_custom_header_background_just_in_time() wp-includes/theme.php

Registers the internal custom header and background routines.
add_thickbox() wp-includes/general-template.php

Enqueues the default ThickBox js and css.
wp_auth_check_load() wp-includes/functions.php

Loads the auth check for monitoring whether the user is still logged in.
wp_maybe_load_widgets() wp-includes/functions.php

Determines if Widgets library should be loaded.
WP_Widget_Recent_Comments::__construct() wp-includes/widgets/class-wp-widget-recent-comments.php

Sets up a new Recent Comments widget instance.
WP_Embed::__construct() wp-includes/class-wp-embed.php

Constructor
WP_Admin_Bar::add_menus() wp-includes/class-wp-admin-bar.php

Adds menus to the admin bar.
WP_Admin_Bar::initialize() wp-includes/class-wp-admin-bar.php

Initializes the admin bar.
register_activation_hook() wp-includes/plugin.php

Set the activation hook for a plugin.
register_deactivation_hook() wp-includes/plugin.php

Sets the deactivation hook for a plugin.
WP_Customize_Setting::preview() wp-includes/class-wp-customize-setting.php

Add filters to supply the setting’s value when accessed.
wp_enqueue_media() wp-includes/media.php

Enqueues all scripts, styles, settings, and templates necessary to use all media JS APIs.
wp_playlist_scripts() wp-includes/media.php

Outputs and enqueues default scripts and styles for playlists.
WP_Rewrite::wp_rewrite_rules() wp-includes/class-wp-rewrite.php

Retrieves the rewrite rules.
WP_Rewrite::flush_rules() wp-includes/class-wp-rewrite.php

Removes rewrite rules and then recreate rewrite rules.
add_feed() wp-includes/rewrite.php

Adds a new feed type like /atom1/.
WP_Scripts::__construct() wp-includes/class-wp-scripts.php

Constructor.
WP_Customize_Header_Image_Control::prepare_control() wp-includes/customize/class-wp-customize-header-image-control.php
WP_Customize_Widgets::customize_preview_init() wp-includes/class-wp-customize-widgets.php

Adds hooks for the Customizer preview.
WP_Customize_Widgets::__construct() wp-includes/class-wp-customize-widgets.php

Initial loader.
WP_Customize_Widgets::schedule_customize_register() wp-includes/class-wp-customize-widgets.php

Ensures widgets are available for all types of previews.
wp_set_comment_status() wp-includes/comment.php

Sets the status of a comment.
_WP_Editors::editor_settings() wp-includes/class-wp-editor.php
wp_print_media_templates() wp-includes/media-template.php

Prints the templates used in the media manager.

Changelog

Version Description
1.2.0 Introduced.

© 2003–2022 WordPress Foundation
Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/functions/add_action