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_namestringrequired

The name of the filter hook.

$callbackcallable|string|array|falseoptional

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

Source

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 );
}

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