sp core library.spevent.add

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SPEvent.add() method

Registers a callback that will be invoked whenever the event occurs.

Signature:

add(observer: ISPEventObserver, eventHandler: (eventArgs: TEventArgs) => void): void;

Parameters

Parameter	Type	Description
observer	ISPEventObserver	Indicates the object that is subscribing to the event: When the object is disposed, the event handler will be automatically removed. This object is also used for diagnostic purposes, e.g. detecting if the event handler failed to catch an exception.
eventHandler	(eventArgs: TEventArgs) => void	A callback function that will be invoked whenever the event occurs

Returns:

void

Remarks

The same object can add multiple event handlers to the same event. Since BaseComponent implements the ISPEventObserver interface, a web part or extension can pass itself as the observer. This will cause the event handler to be automatically unsubscribed when the web part or extension is disposed.