About event and visitor functions

Event and visitor functions are invoked after the event or visitor is processed. You can use event and visitor functions to retrieve data from other systems, augment Tealium data, or send data to other endpoints. To retrieve data from other systems, a function typically requires authentication for that system. For information on adding authentication to an event or visitor function, see Adding an Authentication to a Function.

Action V2 and Action V3 runtimes

The input data for event and visitor functions varies depending on the function type (event or visitor) and the runtime version (Action V2 or Action V3). Functions that use the Action V2 runtime have named exports for input data. Functions that use the Action V3 runtime receive data as input parameters.

In addition, V2 and V3 event and visitor functions differ in how they do the following:

• Get authentication for a service provider.
• Send an event to Tealium Collect.
• Retrieve global variables.
• Get an attribute name or value by attribute ID.
• Make an HTTP request using the fetch() API.

For more information, see:

• Migrate a V2 function to the V3 runtime
• Event and visitor functions V2
• Event and visitor functions V3