Sometimes it makes sense to want to fire an event from an element off to multiple controllers (if the element is a child of both controller scopes). Luckily this is something that was considered by the Stimulus team and it works out of the box.
<input type="email" name="email" data-action="email#change form#change" />
In this example, both
FormController#change would be called with the change event. There are many use-cases for this - in the above example your
EmailController might be looking to validate that email with an external service while a
FormController might be interested in toggling other relevant parts of the form for display.