optimizely-manager.js

/**
 * Optimizely Node Datafile Manager
 *
 *
 * USAGE - INSTALLATION
 *   // Pre-requisites: npm install --save request-promise request @optimizely/optimizely-sdk
 *   // Save this file in a file named optimizely-manager.js
 *   const createOptimizelyManager = require('./optimizely-manager')
 *   const optimizelyManager = createOptimizelyManager('Ly8FQj6vSaDcZUjySoWnWz')
 *
 * USAGE - USING A FEATURE FLAG
 *   const optimizelyClient = optimizelyManager.getClient()
 *   const enabled = optimizelyClient.isFeatureEnabled('sale_price', userId);
 *
 */
const request = require('request-promise');
const assert = require('assert');
const optimizely = require('@optimizely/optimizely-sdk');

module.exports = (SDK_KEY) => {

  let currentDatafile = {};
  let optimizelyClientInstance =  optimizely.createInstance({ datafile: currentDatafile });

  function pollForDatafile() {
    // Request the datafile every second. If the datafile has changed
    // since the last time we've seen it, then re-instantiate the client
    const DATAFILE_URL = `https://cdn.optimizely.com/datafiles/${SDK_KEY}.json`;
    request(DATAFILE_URL)
      .then(async (latestDatafile) => {
        try {
          assert.deepEqual(currentDatafile, latestDatafile)
        } catch (err) {
          console.log('Got a new datafile!')
          // The datafile is different! Let's re-instantiate the client
          optimizelyClientInstance = optimizely.createInstance({ latestDatafile });
          currentDatafile = latestDatafile;
        }
      })
  }

  setInterval(pollForDatafile, 1000);

  return {
    getClient: () => {
      return optimizelyClientInstance;
    }
  }
}