WordPress Performance: Hook System: Advanced Customisation

Hooks are the backbone of extensibility in WordPress. Mastering them lets you customise without modifying core code.

Here’s how to go beyond add_action() and add_filter() basics.

1. Actions vs Filters

Actions do something:

add_action( 'init', 'register_custom_post_type' );

Filters modify and return something:

add_filter( 'the_title', 'prefix_title' );

2. Priority and Arguments

Hooks accept priority and argument count:

add_filter( 'the_content', 'add_cta', 20, 1 );

• Lower priority runs earlier
• Use argument count to match parameters:

add_filter( 'excerpt_more', 'custom_ellipsis', 10, 2 );

3. Anonymous Functions

For inline logic:

add_action( 'wp_footer', function() {
    echo '<!-- Tracking code -->';
});

Note: Harder to remove later.

4. Remove Hooks

Remove default behaviour:

remove_action( 'wp_head', 'wp_generator' );

Remove plugin logic conditionally:

remove_filter( 'the_content', 'some_plugin_output' );

5. Custom Hooks

Create your own in plugins or themes:

do_action( 'myplugin_before_form' );

And listen for them elsewhere:

add_action( 'myplugin_before_form', 'custom_notice' );

6. Debugging Hook Order

Use did_action() or current_filter() to introspect:

if ( did_action('init') ) { log_it('Init has run'); }
echo current_filter();

Plugins like Query Monitor can show live hook firing order.

7. Best Practices

• Prefix hook names to avoid clashes: prefix_hook_name
• Document expected arguments in custom hooks
• Avoid excessive nested hooks

Real-World Application

In a modular theme refactor for a performance project:

• Custom hooks defined around template parts
• Filters used to modify menu logic, breadcrumbs, and excerpts
• Action priorities adjusted for third-party plugin compatibility

Related Reading

• Caching Strategies for WordPress
• Database Optimisation Techniques