has_filter

Syntax

bool has_filter ( 
	string $event_name,
	callable $callback_name = false
);

WordPress codex

Description

It does two different tasks:

• If you don’t pass in your callback name, then it checks if any callbacks are registered to the specified event.
• Else, it checks if the callback (your function, method, or closure) is registered to a specific filter hook event.

Parameters

event_name

The name of the event (filter hook) you want to check.

callback_name

The fully qualified name of your callback.

Return Values

It returns:

• If you pass in a callback, then it returns the priority number for your callback if it is registered; else you’ll get a FALSE back.
• Otherwise, it turns TRUE if there are callbacks are registered; else FALSE is returned.