Subscription

Subscription object is returned by Chart Methods. This object allows you to subscribe and unsubscribe to a chart event. It has two methods:

subscribe(object, method, singleshot)

1. object is a context to be used as this pointer for the method function. Use null if you don't need the context.
2. method is a function to be called when the event happens.
3. singleshot is an optional argument. Set it to true if you wish to be unsubscribed automatically when the event happens for the first time.

unsubscribe(object, method)

Use the same object and method that you used in the subscribe function to unsubscribe from the event.

unsubscribeAll(object)

Use the same object that you used in subscribe function to unsubscribe object from all events.