10 Matching Annotations
  1. Jan 2021
  2. Dec 2020
    1. For example, an event handler callback that can be used to handle both fullscreenchange and fullscreenerror might look like this:
    1. A listener watches for an event to be fired. For example, a KeyListener waits for KeyEvents, a MessageListener waits for messages to arrive on a queue and so on. The handler is responsible for dealing with the event. Normally, listeners and handlers go hand-in-hand. For example, the KeyListener tells the ExitHandler that "the letter Q was pressed" and the handler performs logic such as cleaning up resources and exiting the application gracefully. Similary a ButtonClickListener would tell the same ExitHandler that the "Exit button was clicked". So, in this case you have two different events, two different listeners but a single handler.

      You can use the same handler for multiple events/listeners.

    2. The most basic difference is the association Listener is associated with Event Source (Ex: key board) Handler is associated with an Event (Ex: keydown)