4. Create a subscription callback, which is triggered when an event is received. The data returned by the subscription callback contains information such as the common event name and data carried by the publisher. For details about the data types and parameters of the common event data, see [CommonEventData](../reference/apis/js-apis-commonEvent.md#commoneventdata).
This sample shows how to use **CommonEvent** APIs in Extended TypeScript (eTS) to create subscribers and subscribe to, publish, and unsubscribe from common events.