packages/optimizely-sdk/lib/core/event_builder/index.js
function getImpressionEventParams(configObj, experimentId, variationId) {
  var impressionEventParams = {
      decisions: [{
        campaign_id: projectConfig.getLayerId(configObj, experimentId),
        experiment_id: experimentId,
        variation_id: variationId,
      }],
      events: [{
        entity_id: projectConfig.getLayerId(configObj, experimentId),
        timestamp: fns.currentTimestamp(),
        key: ACTIVATE_EVENT_KEY,
        uuid: fns.uuid(),
      }]

    };
  return impressionEventParams;
}
function getImpressionEventParams(configObj, experimentId, variationId) {
  var impressionEventParams = {
      decisions: [{
        campaign_id: projectConfig.getLayerId(configObj, experimentId),
        experiment_id: experimentId,
        variation_id: variationId,
      }],
      events: [{
        entity_id: projectConfig.getLayerId(configObj, experimentId),
        timestamp: fns.currentTimestamp(),
        key: ACTIVATE_EVENT_KEY,
        uuid: fns.uuid(),
      }]

    };
  return impressionEventParams;
}
function getImpressionEventParams ( configObj , experimentId , variationId ) { var impressionEventParams = { decisions : [ { campaign_id : projectConfig . getLayerId ( configObj , experimentId ) , experiment_id : experimentId , variation_id : variationId , } ] , events : [ { entity_id : projectConfig . getLayerId ( configObj , experimentId ) , timestamp : fns . currentTimestamp ( ) , key : ACTIVATE_EVENT_KEY , uuid : fns . uuid ( ) , } ] } ; return impressionEventParams ; }
Creates object of params specific to impression events
@param  {Object} configObj    Object representing project configuration
@param  {string} experimentId ID of experiment for which impression needs to be recorded
@param  {string} variationId  ID for variation which would be presented to user
@return {Object}              Impression event params
Creates object of params specific to impression events