Singleton Event Dispatcher

This JavaScript event dispatcher creates a Singleton instance and attaches it globally to the page. This event dispatcher is useful when multiple independent component within a page must communicate among them.

See Demo

Usage

Instantiation

Include the following script within your page:

<script src="https://hylasoft-usa.github.io/singleton-event-dispatcher/EventManager.js" type="text/javascript"></script>

Event Manager can be created multiple times by independent component within a page. Passing a true argument, Event Manager constructor will check whether an EventManager instance has already been created keeping the Singleton pattern.

new EventManager(true)

The Event Manager instance can be called in the following way:

window.eventManager

Subscription

This command subscribe the callback function 'foo' to an event EVENT_1

window.eventManager.subscribe("EVENT_1", foo)

'foo' can be subscribed only once to the same event. In case of multiple subscriptions of the same function to an event, Event Manager will just discard the subscription request.

Unsubscribe

This command unsubscribe the callback function 'foo' to an event EVENT_1

window.eventManager.unsubscribe("EVENT_1", foo)

Dispatch

This command dispatches 'EVENT_1'. All the callbacks subscribed for 'EVENT_1' will be called with a payload "Some message" as argument.

window.eventManager.dispatch("EVENT_1", "Some message")

Show all subscription

This command is used for debugging purposes, it shows all the callbacks that are subscribed to all the events.

window.eventManager.showAllSubsriptions()