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has_filter( string $hook_name, callable|string|array|false $callback = false ): bool|int

Checks if any filter has been registered for a hook.

Description

When using the $callback argument, this function may return a non-boolean value that evaluates to false (e.g. 0), so use the === operator for testing the return value.

Parameters

$hook_name string Required
The name of the filter hook.
$callback callable|string|array|false Optional
The callback to check for.
This function can be called unconditionally to speculatively check a callback that may or may not exist.

Default: false

Return

bool|int If $callback is omitted, returns boolean for whether the hook has anything registered. When checking a specific function, the priority of that hook is returned, or false if the function is not attached.

Source

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

function has_filter( $hook_name, $callback = false ) {
	global $wp_filter;

	if ( ! isset( $wp_filter[ $hook_name ] ) ) {
		return false;
	}

	return $wp_filter[ $hook_name ]->has_filter( $hook_name, $callback );
}

Used By

Used By Description
core_auto_updates_settings() wp-admin/update-core.php

Display WordPress auto-updates settings.
WP_Site_Health::detect_plugin_theme_auto_update_issues() wp-admin/includes/class-wp-site-health.php

Checks for potential issues with plugin and theme auto-updates.
WP_Site_Health::check_wp_version_check_exists() wp-admin/includes/class-wp-site-health.php

Tests whether wp_version_check is blocked.
WP_Site_Health_Auto_Updates::test_wp_version_check_attached() wp-admin/includes/class-wp-site-health-auto-updates.php

Checks if updates are intercepted by a filter.
update_sitemeta_cache() wp-includes/ms-site.php

Updates metadata cache for list of site IDs.
do_blocks() wp-includes/blocks.php

Parses dynamic blocks out of post_content and re-renders them.
_restore_wpautop_hook() wp-includes/blocks.php

If do_blocks() needs to remove wpautop() from the the_content filter, this re-adds it afterwards, for subsequent the_content usage.
wpdb::placeholder_escape() wp-includes/class-wpdb.php

Generates and returns a placeholder escape string for use in queries returned by ::prepare().
apply_filters_deprecated() wp-includes/plugin.php

Fires functions attached to a deprecated filter hook.
WP_Customize_Nav_Menu_Item_Setting::preview() wp-includes/customize/class-wp-customize-nav-menu-item-setting.php

Handle previewing the setting.
WP_MS_Sites_List_Table::column_plugins() wp-admin/includes/class-wp-ms-sites-list-table.php

Handles the plugins column output.
Core_Upgrader::upgrade() wp-admin/includes/class-core-upgrader.php

Upgrade WordPress core.
WP_MS_Sites_List_Table::get_columns() wp-admin/includes/class-wp-ms-sites-list-table.php
map_meta_cap() wp-includes/capabilities.php

Maps a capability to the primitive capabilities required of the given user to satisfy the capability being checked.
WP::build_query_string() wp-includes/class-wp.php

Sets the query string property based off of the query variable property.
WP_Widget_Text::widget() wp-includes/widgets/class-wp-widget-text.php

Outputs the content for the current Text widget instance.
WP_Embed::shortcode() wp-includes/class-wp-embed.php

The do_shortcode() callback function.
has_action() wp-includes/plugin.php

Checks if any action has been registered for a hook.
wp_update_comment() wp-includes/comment.php

Updates an existing comment in the database.
sanitize_meta() wp-includes/meta.php

Sanitizes meta value.
register_meta() wp-includes/meta.php

Registers a meta key.
_WP_Editors::editor() wp-includes/class-wp-editor.php

Outputs the HTML for a single instance of the editor.

Changelog

Version Description
2.5.0 Introduced.

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