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Set up a notification listener using the JavaScript (Browser) SDK

This topic describes how to set up and remove notification listeners for the Optimizely Feature Experimentation JavaScript (Browser) SDK.

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.

Notification listener types

For more information about notification listener types and use cases, see Notification listeners.

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Note

The follow code examples assume you have already initialized the JavaScript (Browser) SDK and have created an optimizelyClient instance.

Add and remove all notification listeners

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/optimizely-sdk';

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

// Add Notification Listener
const notificationId = optimizely.notificationCenter.addNotificationListener(
  enums.NOTIFICATION_TYPES.DECISION,
  ({ type, userId, attributes, decisionInfo }) => {
    console.log(type, userId, attributes, decisionInfo);
  },
);

// Remove Notification Listener
optimizely.notificationCenter.removeNotificationListener(notificationId);

// Remove All Notification Listeners
optimizely.notificationCenter.clearAllNotificationListeners();

// Remove all Notification Listeners of a certain type
optimizely.notificationCenter.clearNotificationListeners(enums.NOTIFICATION_TYPES.DECISION);

Set up each type of notification listener

The example code below shows how to set up each type of notification listener.

import { createInstance, enums } from '@optimizely/optimizely-sdk';
// import your third-party analytics integration here

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


///////////////////////////////////////////
// SET UP DECISION NOTIFICATION LISTENER //
///////////////////////////////////////////
const onDecision = ({ type, userId, attributes, decisionInfo }) => {
  // Add a DECISION Notification Listener for type FLAG
  if (type === 'flag') {
    // Access information about feature, for example, key and enabled status
    console.log(decisionInfo['flagKey']);
    console.log(decisionInfo['enabled']);
    console.log(decisionInfo['decisionEventDispatched']);
    // Send data to analytics provider here
  }
}

const notificationId = optimizely.notificationCenter.addNotificationListener(
  enums.NOTIFICATION_TYPES.DECISION, onDecision,
);

////////////////////////////////////////////
// SET UP LOG EVENT NOTIFICATION LISTENER //
////////////////////////////////////////////
const onLogEvent = (logEvent) => {
  // process the logEvent object here (send to analytics provider, audit/inspect data)
}

optimizely.notificationCenter.addNotificationListener(
  enums.NOTIFICATION_TYPES.LOG_EVENT, onLogEvent
);

////////////////////////////////////////////////////
// SET UP OPTIMIZELY CONFIG NOTIFICATION LISTENER //
////////////////////////////////////////////////////
// listen to OPTIMIZELY_CONFIG_UPDATE to get updated data
// You will get notifications whenever the datafile is updated except for SDK initialization
const onConfigUpdateListener = () => {
  const config = optimizelyClient.getOptimizelyConfig()
}

optimizely.notificationCenter.addNotificationListener(
  enums.NOTIFICATION_TYPES.OPTIMIZELY_CONFIG_UPDATE,
  onConfigUpdateListener
);


////////////////////////////////////////
// SET UP TRACK NOTIFICATION LISTENER //
////////////////////////////////////////
const onTrack = (event) => {
  // process the event here (send to analytics provider, audit/inspect data)
}

optimizely.notificationCenter.addNotificationListener(
  enums.NOTIFICATION_TYPES.TRACK,
  onTrack
);