Common WordPress Hooks Reference

Introduction

This is a quick reference guide to the most frequently used WordPress hooks. These are the hooks you'll use in 90% of your WordPress development work.

Hook Categories

WordPress hooks are organized by functionality:

WORDPRESS HOOKS STRUCTURE
=========================

Initialization Hooks
├── plugins_loaded
├── init
├── after_setup_theme
└── wp_loaded

Template Hooks
├── wp_head
├── wp_footer
├── get_header
├── get_sidebar
└── get_footer

Content Hooks (Filters)
├── the_title
├── the_content
├── the_excerpt
└── body_class

Script/Style Hooks
├── wp_enqueue_scripts
├── admin_enqueue_scripts
└── login_enqueue_scripts

Admin Hooks
├── admin_menu
├── admin_init
├── save_post
└── admin_notices

User Hooks
├── user_register
├── wp_login
└── wp_logout

Initialization Hooks

`plugins_loaded`

Type: Action

When: After all plugins are loaded

Use: Plugin initialization, check for other plugins

add_action('plugins_loaded', 'my_plugin_init');

function my_plugin_init() {
    // Check if another plugin is active
    if (class_exists('WooCommerce')) {
        // Initialize WooCommerce integration
    }

    // Load text domain for translations
    load_plugin_textdomain('my-plugin', false, dirname(plugin_basename(__FILE__)) . '/languages');
}

`init`

Type: Action

When: WordPress initialization complete

Use: Register post types, taxonomies, shortcodes

add_action('init', 'my_custom_init');

function my_custom_init() {
    // Register custom post type
    register_post_type('book', [
        'public' => true,
        'label' => 'Books',
        'has_archive' => true,
    ]);

    // Register custom taxonomy
    register_taxonomy('genre', 'book', [
        'label' => 'Genres',
        'hierarchical' => true,
    ]);

    // Register shortcode
    add_shortcode('my_shortcode', 'my_shortcode_handler');
}

`after_setup_theme`

Type: Action

When: After theme is loaded

Use: Theme setup, add theme support

add_action('after_setup_theme', 'my_theme_setup');

function my_theme_setup() {
    // Add theme support
    add_theme_support('post-thumbnails');
    add_theme_support('custom-logo');
    add_theme_support('title-tag');

    // Register navigation menus
    register_nav_menus([
        'primary' => 'Primary Menu',
        'footer' => 'Footer Menu',
    ]);
}

`wp_loaded`

Type: Action

When: Everything is loaded (WordPress, plugins, theme)

Use: Operations requiring everything to be ready

add_action('wp_loaded', 'my_custom_operation');

function my_custom_operation() {
    // Everything is loaded, safe to use any WordPress function
    if (is_user_logged_in()) {
        // Do something for logged-in users
    }
}

Frontend Template Hooks

`wp_head`

Type: Action

When: Inside <head> section before </head>

Use: Add meta tags, inline CSS, tracking codes

add_action('wp_head', 'add_custom_meta_tags');

function add_custom_meta_tags() {
    ?>
    <meta name="author" content="John Doe">
    <meta name="description" content="<?php echo get_the_excerpt(); ?>">
    <link rel="preconnect" href="https://fonts.googleapis.com">
    <?php
}

`wp_footer`

Type: Action

When: Before closing </body> tag

Use: Add scripts, analytics, modals, pop-ups

add_action('wp_footer', 'add_analytics_code');

function add_analytics_code() {
    ?>
    <script>
        // Google Analytics
        gtag('config', 'GA_MEASUREMENT_ID');
    </script>
    <?php
}

`get_header`

Type: Action

When: After header.php is loaded

Use: Modify header output

add_action('get_header', 'my_header_customization');

function my_header_customization() {
    // Add something after header
    echo '<div class="site-announcement">Special Offer!</div>';
}

`get_sidebar`

Type: Action

When: After sidebar.php is loaded

Use: Modify sidebar

add_action('get_sidebar', 'add_sidebar_ad');

function add_sidebar_ad() {
    echo '<div class="sidebar-ad">Advertisement</div>';
}

`get_footer`

Type: Action

When: After footer.php is loaded

Use: Modify footer

add_action('get_footer', 'add_footer_widgets');

function add_footer_widgets() {
    dynamic_sidebar('footer-widgets');
}

Content Filters

`the_title`

Type: Filter

When: Post/page title is displayed

Parameters: $title, $post_id

Use: Modify post titles

add_filter('the_title', 'customize_title', 10, 2);

function customize_title($title, $post_id) {
    // Add emoji to product titles
    if (get_post_type($post_id) === 'product') {
        $title = '🛍️ ' . $title;
    }

    return $title;
}

`the_content`

Type: Filter

When: Post content is displayed

Parameters: $content

Use: Modify post content

add_filter('the_content', 'add_content_footer');

function add_content_footer($content) {
    // Only on single posts
    if (is_single()) {
        $footer = '<div class="content-footer">';
        $footer .= '<p>Share this article!</p>';
        $footer .= '</div>';

        $content .= $footer;
    }

    return $content;
}

`the_excerpt`

Type: Filter

When: Post excerpt is displayed

Parameters: $excerpt

Use: Modify excerpt

add_filter('the_excerpt', 'custom_excerpt');

function custom_excerpt($excerpt) {
    return $excerpt . ' <a href="' . get_permalink() . '">Read More &rarr;</a>';
}

`excerpt_length`

Type: Filter

When: Excerpt length is determined

Parameters: $length

Use: Change excerpt word count

add_filter('excerpt_length', 'custom_excerpt_length');

function custom_excerpt_length($length) {
    return 30; // Change from default 55 to 30 words
}

`excerpt_more`

Type: Filter

When: Excerpt "more" indicator is displayed

Parameters: $more

Use: Change [...] text

add_filter('excerpt_more', 'custom_excerpt_more');

function custom_excerpt_more($more) {
    return '... <a href="' . get_permalink() . '" class="read-more">Continue Reading</a>';
}

CSS Class Filters

`body_class`

Type: Filter

When: Body CSS classes are output

Parameters: $classes (array)

Use: Add custom body classes

add_filter('body_class', 'custom_body_classes');

function custom_body_classes($classes) {
    // Add logged-in class
    if (is_user_logged_in()) {
        $classes[] = 'user-logged-in';
    }

    // Add browser-specific class
    if (strpos($_SERVER['HTTP_USER_AGENT'], 'Safari') !== false) {
        $classes[] = 'safari';
    }

    return $classes;
}

`post_class`

Type: Filter

When: Post CSS classes are output

Parameters: $classes, $class, $post_id

Use: Add custom post classes

add_filter('post_class', 'custom_post_classes', 10, 3);

function custom_post_classes($classes, $class, $post_id) {
    // Add featured class if post has thumbnail
    if (has_post_thumbnail($post_id)) {
        $classes[] = 'has-featured-image';
    }

    return $classes;
}

Script and Style Hooks

`wp_enqueue_scripts`

Type: Action

When: Frontend scripts/styles should be enqueued

Use: Add CSS/JS files to frontend

add_action('wp_enqueue_scripts', 'enqueue_custom_assets');

function enqueue_custom_assets() {
    // Enqueue stylesheet
    wp_enqueue_style(
        'custom-style',
        get_template_directory_uri() . '/css/custom.css',
        [],
        '1.0.0'
    );

    // Enqueue script
    wp_enqueue_script(
        'custom-script',
        get_template_directory_uri() . '/js/custom.js',
        ['jquery'],
        '1.0.0',
        true
    );

    // Pass data to JavaScript
    wp_localize_script('custom-script', 'myData', [
        'ajaxUrl' => admin_url('admin-ajax.php'),
        'nonce' => wp_create_nonce('my-nonce'),
    ]);
}

`admin_enqueue_scripts`

Type: Action

When: Admin scripts/styles should be enqueued

Parameters: $hook (current admin page)

Use: Add CSS/JS to admin area

add_action('admin_enqueue_scripts', 'enqueue_admin_assets');

function enqueue_admin_assets($hook) {
    // Only load on our custom page
    if ($hook !== 'toplevel_page_my-plugin') {
        return;
    }

    wp_enqueue_style('my-admin-style', plugins_url('css/admin.css', __FILE__));
    wp_enqueue_script('my-admin-script', plugins_url('js/admin.js', __FILE__));
}

`login_enqueue_scripts`

Type: Action

When: Login page scripts/styles should be enqueued

Use: Customize login page

add_action('login_enqueue_scripts', 'custom_login_styles');

function custom_login_styles() {
    ?>
    <style>
        #login h1 a {
            background-image: url('<?php echo get_template_directory_uri(); ?>/images/logo.png');
            width: 200px;
            height: 100px;
            background-size: contain;
        }
    </style>
    <?php
}

Admin Hooks

`admin_menu`

Type: Action

When: Admin menu is being constructed

Use: Add admin menu pages

add_action('admin_menu', 'add_custom_admin_page');

function add_custom_admin_page() {
    add_menu_page(
        'My Plugin Settings',           // Page title
        'My Plugin',                    // Menu title
        'manage_options',               // Capability
        'my-plugin-settings',           // Menu slug
        'render_my_plugin_page',        // Callback function
        'dashicons-admin-generic',      // Icon
        20                              // Position
    );

    add_submenu_page(
        'my-plugin-settings',           // Parent slug
        'Advanced Settings',            // Page title
        'Advanced',                     // Menu title
        'manage_options',               // Capability
        'my-plugin-advanced',           // Menu slug
        'render_advanced_page'          // Callback
    );
}

function render_my_plugin_page() {
    ?>
    <div class="wrap">
        <h1>My Plugin Settings</h1>
        <form method="post" action="options.php">
            <?php
            settings_fields('my-plugin-settings');
            do_settings_sections('my-plugin-settings');
            submit_button();
            ?>
        </form>
    </div>
    <?php
}

`admin_init`

Type: Action

When: Admin area is initialized

Use: Register settings, redirect, check permissions

add_action('admin_init', 'register_my_settings');

function register_my_settings() {
    // Register setting
    register_setting('my-plugin-settings', 'my_option');

    // Add settings section
    add_settings_section(
        'my-settings-section',
        'General Settings',
        'my_settings_section_callback',
        'my-plugin-settings'
    );

    // Add settings field
    add_settings_field(
        'my-field',
        'My Setting',
        'my_field_callback',
        'my-plugin-settings',
        'my-settings-section'
    );
}

function my_settings_section_callback() {
    echo '<p>Configure your settings below:</p>';
}

function my_field_callback() {
    $value = get_option('my_option', '');
    echo '<input type="text" name="my_option" value="' . esc_attr($value) . '">';
}

`save_post`

Type: Action

When: Post is saved

Parameters: $post_id, $post, $update

Use: Save custom data, trigger actions

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

function save_custom_metadata($post_id, $post, $update) {
    // Don't save during autosave
    if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) {
        return;
    }

    // Check user permissions
    if (!current_user_can('edit_post', $post_id)) {
        return;
    }

    // Check nonce
    if (!isset($_POST['my_nonce']) || !wp_verify_nonce($_POST['my_nonce'], 'my_action')) {
        return;
    }

    // Save custom field
    if (isset($_POST['custom_field'])) {
        update_post_meta($post_id, '_custom_field', sanitize_text_field($_POST['custom_field']));
    }

    // Clear cache when post is updated
    if ($update) {
        delete_transient('homepage_posts');
    }
}

`admin_notices`

Type: Action

When: Admin notices should be displayed

Use: Show admin messages

add_action('admin_notices', 'show_custom_notice');

function show_custom_notice() {
    $screen = get_current_screen();

    if ($screen->id === 'edit-post') {
        ?>
        <div class="notice notice-info is-dismissible">
            <p>Welcome to the post editor!</p>
        </div>
        <?php
    }
}

User Hooks

`user_register`

Type: Action

When: New user is registered

Parameters: $user_id

Use: Set up new user data, send welcome email

add_action('user_register', 'setup_new_user', 10, 1);

function setup_new_user($user_id) {
    // Add custom user meta
    add_user_meta($user_id, 'registration_date', current_time('mysql'));

    // Send welcome email
    $user = get_userdata($user_id);
    wp_mail(
        $user->user_email,
        'Welcome to our site!',
        'Thank you for registering...'
    );

    // Add to mailing list
    subscribe_to_newsletter($user->user_email);
}

`wp_login`

Type: Action

When: User logs in

Parameters: $user_login, $user

Use: Track logins, redirect, update data

add_action('wp_login', 'track_user_login', 10, 2);

function track_user_login($user_login, $user) {
    // Update last login time
    update_user_meta($user->ID, 'last_login', current_time('mysql'));

    // Log the login
    error_log("User {$user_login} logged in");

    // Increment login count
    $login_count = get_user_meta($user->ID, 'login_count', true);
    update_user_meta($user->ID, 'login_count', $login_count + 1);
}

`wp_logout`

Type: Action

When: User logs out

Use: Clean up session data, track logouts

add_action('wp_logout', 'handle_user_logout');

function handle_user_logout() {
    $user_id = get_current_user_id();

    // Update logout time
    update_user_meta($user_id, 'last_logout', current_time('mysql'));

    // Clear custom session data
    delete_user_meta($user_id, 'temp_session_data');
}

Comment Hooks

`comment_post`

Type: Action

When: Comment is posted

Parameters: $comment_id, $comment_approved

Use: Process comments, notifications

add_action('comment_post', 'notify_on_comment', 10, 2);

function notify_on_comment($comment_id, $comment_approved) {
    if ($comment_approved === 1) {
        $comment = get_comment($comment_id);
        $post = get_post($comment->comment_post_ID);

        // Notify post author
        wp_mail(
            get_the_author_meta('user_email', $post->post_author),
            'New comment on your post',
            "Someone commented on: {$post->post_title}"
        );
    }
}

`comment_text`

Type: Filter

When: Comment text is displayed

Parameters: $comment_text

Use: Modify comment display

add_filter('comment_text', 'highlight_admin_comments');

function highlight_admin_comments($comment_text) {
    $comment = get_comment();

    if (user_can($comment->user_id, 'administrator')) {
        $comment_text = '<div class="admin-comment">' . $comment_text . '</div>';
    }

    return $comment_text;
}

`widgets_init`

Type: Action

When: Widgets are initialized

Use: Register widget areas, custom widgets

add_action('widgets_init', 'register_custom_sidebars');

function register_custom_sidebars() {
    // Register sidebar
    register_sidebar([
        'name' => 'Footer Sidebar',
        'id' => 'footer-sidebar',
        'before_widget' => '<div class="widget">',
        'after_widget' => '</div>',
        'before_title' => '<h3 class="widget-title">',
        'after_title' => '</h3>',
    ]);

    // Register custom widget
    register_widget('My_Custom_Widget');
}

Query Hooks

`pre_get_posts`

Type: Action

When: Before posts are queried

Parameters: $query (WP_Query object)

Use: Modify queries

add_action('pre_get_posts', 'modify_main_query');

function modify_main_query($query) {
    // Only modify main query on frontend
    if (!is_admin() && $query->is_main_query()) {
        // Show 20 posts on blog page
        if ($query->is_home()) {
            $query->set('posts_per_page', 20);
        }

        // Exclude category from blog
        if ($query->is_home()) {
            $query->set('cat', '-5'); // Exclude category ID 5
        }
    }
}

Quick Reference Tables

Most Common Actions

Hook	When	Common Use
`init`	WordPress loaded	Register CPTs, taxonomies
`wp_enqueue_scripts`	Enqueue time (frontend)	Add CSS/JS
`admin_enqueue_scripts`	Enqueue time (admin)	Add admin CSS/JS
`wp_head`	In `<head>`	Meta tags, CSS
`wp_footer`	Before `</body>`	Scripts, analytics
`admin_menu`	Building admin menu	Add admin pages
`save_post`	Post saved	Save metadata
`user_register`	User registered	Welcome email
`wp_login`	User logged in	Track login

Most Common Filters

Hook	What It Filters	Common Use
`the_title`	Post title	Modify titles
`the_content`	Post content	Add content
`the_excerpt`	Post excerpt	Customize excerpt
`body_class`	Body CSS classes	Add classes
`post_class`	Post CSS classes	Conditional classes
`excerpt_length`	Excerpt word count	Change length
`login_redirect`	Login redirect URL	Custom redirect
`upload_mimes`	Allowed file types	Add file types

Summary

This reference covers the most essential WordPress hooks. Remember:

Actions: Use to execute code at specific points
Filters: Use to modify data before it's used
Check the WordPress Developer Reference for complete documentation
Use appropriate hooks for your specific needs
Always check if you're in the right context (frontend/admin/etc.)

Introduction

Hook Categories

Initialization Hooks

plugins_loaded

init

after_setup_theme

wp_loaded

Frontend Template Hooks

wp_head

wp_footer

get_header

get_sidebar

get_footer

Content Filters

the_title

the_content

the_excerpt

excerpt_length

excerpt_more

CSS Class Filters

body_class

post_class

Script and Style Hooks

wp_enqueue_scripts

admin_enqueue_scripts

login_enqueue_scripts

Admin Hooks

admin_menu

admin_init

save_post

admin_notices

User Hooks

user_register

wp_login

wp_logout

Comment Hooks

comment_post

comment_text

Widget Hooks

widgets_init

Query Hooks

pre_get_posts

Quick Reference Tables

Most Common Actions

Most Common Filters

Summary

`plugins_loaded`

`init`

`after_setup_theme`

`wp_loaded`

`wp_head`

`wp_footer`

`get_header`

`get_sidebar`

`get_footer`

`the_title`

`the_content`

`the_excerpt`

`excerpt_length`

`excerpt_more`

`body_class`

`post_class`

`wp_enqueue_scripts`

`admin_enqueue_scripts`

`login_enqueue_scripts`

`admin_menu`

`admin_init`

`save_post`

`admin_notices`

`user_register`

`wp_login`

`wp_logout`

`comment_post`

`comment_text`

`widgets_init`

`pre_get_posts`