Node SDK

alias

Migrate events from one known ID to another known ID.

analytics.alias({
  userId: 'canonical-user-123',
  previousId: 'legacy-user-456',
})

Ferno reassigns all previous events for previousId to userId. Use this only for known-ID migration or merging duplicate known accounts:

Legacy ID to canonical ID migration.
Duplicate customer-record merge.
Account-model consolidation.
Database import or identity repair.

Do not call alias after ordinary authentication or when a user switches accounts. Call identify for the authenticated account instead. Alias would incorrectly merge separate users.

{
  "type": "alias",
  "userId": "canonical-user-123",
  "previousId": "legacy-user-456"
}

Optional fields are context, timestamp, integrations, and messageId. The callback is the second argument.

PreviousIdentify NextPage