..  include:: /Includes.rst.txt
..  index:: JavaScript; Throttle event
..  _Events_JavaScript_Throttle:

==============
Throttle event
==============

A "throttled event" executes its handler after a configured waiting time over a time span. This event type is similar to
the debounced event, where the major difference is that a throttled event executes its listeners multiple times.

To construct the event listener, the module :js:`TYPO3/CMS/Core/Event/ThrottleEvent` must be imported. The constructor
accepts the following arguments:

*   :js:`eventName` (string) - the event to listen on
*   :js:`callback` (function) - the executed event listener when the event is triggered
*   :js:`limit` (number) - the amount of milliseconds to wait until the event listener is executed again

..  hint::
    If an event spans over 2000ms and the wait time is configured to be 100ms,
    the event listener gets called up to 20 times in total (:math:`20=\frac{2000}{100}`).

..  code-block:: js

    import ThrottleEvent from '@typo3/core/event/throttle-event.js';

    new ThrottleEvent('mousewheel', function (e) {
        console.log('Executed every 50ms during the overall event time span');
    }, 50).bindTo(document.body);