Hooks & Filters

Theme-level hooks and filters let a theme's functions.php extend behavior without touching core files. (Plugins have a separate, similarly-shaped hook system — see Plugin Basics and Hooks & the Plugin Lifecycle.)

Hooks

Available hooks

All eight are pre-registered. You can pass a custom name to add_theme_action() — it creates the entry on the fly — but do_theme_action() only fires hooks the core or your theme actually calls.

Hook	Fires
`before_header` / `after_header`	Around the `<header>` element
`before_content` / `after_content`	Around the main content area
`before_footer` / `after_footer`	Around the `<footer>` element
`header_scripts`	Inside `<head>`
`footer_scripts`	Before `</body>`

`add_theme_action(string $hook, callable $function, int $priority = 10): bool`

add_theme_action('before_footer', function() {
    echo '<div class="newsletter-banner">Subscribe</div>';
});

Lower $priority runs first.

`do_theme_action(string $hook, mixed $args = null): void`

Executes all callbacks on a hook, in priority order. Called internally by the CMS — rarely needed directly in theme code.

Filters

There are no built-in named filters — any string key works as one.

`add_theme_filter(string $hook, callable $function, int $priority = 10): bool`

The callback receives the current value and must return a value.

add_theme_filter('footer_text', fn($text) => $text . ' — Powered by SynaptikCMS');

`apply_theme_filters(string $hook, mixed $content): mixed`

Passes $content through every filter on $hook, in priority order. Returns $content unchanged if none are registered.

$text = apply_theme_filters('footer_text', $settings['footer_text']);

Theme options

In-memory key/value pairs, scoped to the current request — useful for passing data from functions.php to templates without globals.

set_theme_option('show_sidebar', true);
// ...
if (get_theme_option('show_sidebar')) { include 'sidebar.php'; }

get_theme_option(string $name, mixed $default = null): mixed.

Asset helpers

style.css and script.js are already injected automatically by render_header_scripts() — these are for additional assets only.

`add_theme_stylesheet(string $stylesheet): void`

add_theme_stylesheet('css/custom.css');

`add_theme_script(string $script, bool $in_footer = true): void`

add_theme_script('js/animations.js');

$in_footer = true → footer_scripts hook; false → header_scripts hook.

Page detection

is_home(): bool and is_current_page(string $type, string $slug = ''): bool — see Utility Functions for usage examples.