Check if do_action('custom_action') is hooked into?

Question

Is there a way to check if a custom hook gets called upon? I would like to display a placeholder if no output will be passed to it.

Answer 1

I believe you are looking for has_action, which should ...

Check if any action has been registered for a hook.

if (has_action('custom_action')) {
  // stuff
} else {
  // different stuff
}

Answer 2

Do you know did_action?

If I understood you correctly, you are looking for something like the following:

if (0 === did_action('custom_action')) {
    // placeholder, or whatever
}