Set up notification listener

Notification listeners trigger a callback function that you define when certain actions are triggered in the SDK.

The most common use case is to send a stream of all feature flag decisions to an analytics provider or to an internal data warehouse to join it with other data that you have about your users.

To track feature usage:

1. Sign up for an analytics provider of your choice (for example: Segment)
2. Set up a notification listener of type 'DECISION'
3. Follow your analytics provider's documentation and send events from within the decision listener callback

Steps 1 and 3 are not covered in this documentation. However, setting up a 'DECISION' notification listener is covered below.

Set up a DECISION notification listener

The DECISION notification listener enables you to be notified whenever the SDK determines what decision value to return for a feature. The callback is triggered with the decision type, associated decision information, user ID, and attributes.

DECISION listeners are triggered when your application renders OptimizelyFeature or OptimizelyExperiment or when you call the Is Feature Enabled or Get Enabled Features APIs. DECISION listeners are also triggered in some other cases. Please see the tables at the end of this section for complete detail.

To set up a DECISION listener:

1. Define a callback to be called when the DECISION event is triggered
2. Add the callback to the notification center on the Optimizely instance

The example code below shows how to add a listener, remove a listener, remove all listeners of a specific type (such as all decision listeners), and remove all listeners.

import {
  createInstance,
  enums,
} from '@optimizely/react-sdk';

const optimizely = createInstance({
  sdkKey: '<Your_SDK_Key>',
})

function onDecision(decisionObject) {
  if (decisionObject.type === 'feature') {
    // Access type on decisionObject to get type of decision
    console.log(decisionObject.type);
    // Access decisionInfo on decisionObject which
    // will have form as per type of decision.
    console.log(decisionObject.decisionInfo);

    // Send data to analytics provider here
    // Example:
    //  analytics.track({
    //    userId: decisionObject.userId,
    //    event: decisionObject.type,
    //    properties: decisionObject.decisionInfo,
    //  });
  }
}

// Add a notificaiton listener for the decision notification
const listenerId = optimizely.notificationCenter.addNotificationListener(
  enums.NOTIFICATION_TYPES.DECISION,
  onDecision,
);

// Remove a specific listener
optimizely.notificationCenter.removeNotificationListener(listenerId);

// Remove listeners for a specific notification type
optimizely.notificationCenter.clearNotificationListeners(
  enums.NOTIFICATION_TYPES.DECISION,
);

// Remove all listeners
optimizely.notificationCenter.clearAllNotificationListeners();

The tables below show the information provided to the listener when it is triggered.