[Home](./index.md) > [@snowplow/react-native-tracker](./react-native-tracker.md) > [SessionState](./react-native-tracker.sessionstate.md) > [firstEventId](./react-native-tracker.sessionstate.firsteventid.md) ## SessionState.firstEventId property The optional identifier of the first event for this session Signature: ```typescript firstEventId?: string; ```