featureExperimentationFullStoryIntegration.js

// Constant for consistent event naming
const OPTIMIZELY_EVENT_NAME = 'Optimizely_Experiment';

// Helper function to safely retrieve the FullStory API
// You may want to add code to wait for it to be available
function _fs() {
  const fsNamespace = window['_fs_namespace'];
  const fsApi = fsNamespace && window[fsNamespace];
  return typeof fsApi === 'function' ? fsApi : () => {};
}

// Optimizely decision listener callback
const onDecision = ({ type, userId, attributes, decisionInfo }) => {
  // Defensive: ensure decisionInfo exists and the event was dispatched
  if (decisionInfo && decisionInfo.decisionEventDispatched) {
    const experimentKey = decisionInfo.ruleKey;
    const variationKey = decisionInfo.variationKey;

    const decisionObject = {
      experiment: experimentKey,
      variation: variationKey,
    };

    // Track the decision in FullStory
    _fs()('trackEvent', {
      name: OPTIMIZELY_EVENT_NAME,
      properties: decisionObject,
    });

    // Optional: remove listener if only needed once
    // optimizelyClient.notificationCenter.removeNotificationListener(notificationId);
  }
};

// Register the listener with Optimizely
const notificationId = optimizelyClient.notificationCenter.addNotificationListener(
  enums.NOTIFICATION_TYPES.DECISION,
  onDecision
);