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IAB TCF2.0 Event Listeners

This article describes IAB TCF2.0 event listeners and their use case.

Using _tcfapi() addEventListener and removeEventListener commands

This article describes the addEventListener and removeEventListener commands and how to use them in the __tcfapi() function. 

The addEventListener command is leveraged to listen for changes in the user's consent status during a pageview. This can be used in situations where vendors depend on the TC String's value in order to execute appropriately. 

The removeEventListener command removes the listener created.


The addEventListener command registers a callback function with a CMP. The listener's callback is triggered whenever the consent string status has changed. To set up an event listener you pass three arguments to the __tcfapi() function:

  • the 'addEventListener' command
  • the version of the framework
  • a callback function

The following are the possible events returned.

eventStatus Description
'tcloaded' This is the event status when a TC String is available to any calling scripts on the page. 
'cmpuishown' This is the event status whenever the UI is surfaced or re-surfaced to a user.
'useractioncomplete' This is the event status whenever a user has confirmed or re-confirmed their choices.

The listener is registered with an ID. You can use this ID to remove the event listener at a later date.


The removeEventListener command removes the event listener. To remove an event listener, you pass four arguments to the __tcfapi() function:

  • The 'removeEventListener' command
  • The version number of the framework
  • A callback function
  • The ID of the listener to be removed

If successful the listener is removed and the value of true is passed to the callback function. If it was not successful then it means it could not find a listener with the ID value passed.

Below is an example of the addEventListener and removeEventListener commands being used together.

If you have any additional questions about these functions, please consult the IAB's documentation