2020-05-02 / 2654阅 / 悠然
Check if any filter has been registered for a hook.
(string)
(Required)
The name of the filter hook.
(callable|bool)
(Optional)
The callback to check for.
Default value: false
(false|int) If $function_to_check 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. When using the $function_to_check 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.