Breaking: #101519 - Remove immediate flag in DebounceEvent

See forge#101519

Description

With the introduction in TYPO3 v10, the DebounceEvent module had the possibility to shift the event handler execution to the beginning of the debounce sequence, enabled via the optional immediate parameter.

The parameter is unused in TYPO3 and using this feature has a negative impact on UX. If used, the event handler is directly executed and the user has to wait a specific time after the last event was triggered, before any further execution is possible.

The flag immediate has been therefore removed.

Impact

The DebounceEvent module now always waits until a certain time has passed after the last trigger of the event happened before executing the event handler. This is mostly used in potential heavy tasks, e.g. an AJAX request that is sent depending on the content of a search field.

Affected installations

All extensions using the removed flag are affected.

Migration

There is no direct migration possible. An extension author either may re-implement the removed behavior manually, or use the ThrottleEvent module, providing a similar behavior.