Web CMP Events Guide

The OneTrust Web CMP solution has several JavaScript events to enable your website to respond to changes in a user’s consent.

📘

All events are raised in the window object.

OneTrustGroupsUpdated

This event is triggered each time the script loads, such as when the website is accessed or refreshed, and whenever the user updates their consent preferences.

window.addEventListener("OneTrustGroupsUpdated", event => {
  console.log(`The following groups are now active: ${event.detail.join(", ")}`);
});

Event properties:

OTConsentApplied

This event is triggered when the user's consent status changes and the corresponding consent receipt call has been made. It is similar to the OneTrust.OnConsentChanged method, but occurs later due to its dependency on the consent receipt logging process.

window.addEventListener("OTConsentApplied", event => {
    console.log("The user has updated their consent.");
    console.log(`New consent states: ${OnetrustActiveGroups}`);
});

OnConsentChanged

This public method is triggered when the user's consent status changes. While similar to the OTConsentApplied event, it is invoked earlier because it does not depend on the consent receipt logging workflow.

OneTrust.OnConsentChanged(function() {
  console.log('User consent updated.');
});

OneTrustPCLoaded

This event is triggered when the preference center UI is surfaced. It occurs at the moment the call to open the preference center is made, without waiting for any associated animations to complete.

window.addEventListener("OneTrustPCLoaded", event => {
    console.log("The preference center has been surfaced.");
});

Tips

Actioning consent

Event listeners offer a flexible way to handle consent related logic in modular code outside the scope of the OptanonWrapper. Since they have no dependencies, listeners can be registered at any point in your application's lifecycle, regardless of whether OneTrust has already loaded.

The example below demonstrates how to start and stop a sample myAnalyticsTool based on the user's consent for the 'Performance' category (C0002).

window.addEventListener("OneTrustGroupsUpdated", event => {
    if (event.detail.includes("C0002") && !myAnalyticsTool.isOn) {
        myAnalyticsTool.startCapture();
    } else {
        myAnalyticsTool.stopCapture();
    }
});

Firing Listeners Once

The addEventListener method accepts several options as its third parameter. One particularly useful option is once, which ensures the listener is automatically removed after it handles the event a single time.

window.addEventListener("OneTrustGroupsUpdated", event => {
    console.log("Only fire this listener once.");
}, { once: true });