Node — Alias

Link an alias (e.g. anonymous ID) to a user with signal.alias(). Use when merging anonymous and identified users (e.g. after login). Sends $create_alias.

alias(distinctId, alias, sessionId?, windowId?)

Link an alias (e.g. anonymous ID) to a user. Sends $create_alias event.

Parameter	Type	Required	Description
`distinctId`	`string`	yes	Current user identifier (e.g. after login)
`alias`	`string`	yes	Alias to link (e.g. previous anonymous ID)
`sessionId`	`string`	no	From `x-signal-session-id` header for client correlation
`windowId`	`string`	no	From `x-signal-window-id` header for client correlation

When to use: After login to merge anonymous events (from before login) with the identified user. This ensures all events are associated with the same user profile.

const { sessionId, windowId, distinctId } = getSessionInfo(req);

signal.alias(
  distinctId || userId,
  anonymousId,
  sessionId,
  windowId
);

// After user logs in
const { sessionId, windowId, distinctId } = getSessionInfo(req);

// Identify the user
signal.identify({
  distinctId: userId,
  properties: { email: user.email, name: user.name },
  sessionId,
  windowId,
});

// Link anonymous ID if it exists
if (anonymousId) {
  signal.alias(userId, anonymousId, sessionId, windowId);
}

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Alias

Node — Alias

alias(distinctId, alias, sessionId?, windowId?)

See also

​Node — Alias

​alias(distinctId, alias, sessionId?, windowId?)

​Example: Login flow

​See also

Node — Alias

alias(distinctId, alias, sessionId?, windowId?)

Example: Login flow

See also