How to use @optimizely/js-sdk-datafile-manager - 1 common examples

}
  } else {
    this.__configObj = null;
  }

  if (config.sdkKey) {
    var datafileManagerConfig = {
      sdkKey: config.sdkKey,
    };
    if (this.__validateDatafileOptions(config.datafileOptions)) {
      fns.assign(datafileManagerConfig, config.datafileOptions);
    }
    if (initialDatafile && this.__configObj) {
      datafileManagerConfig.datafile = initialDatafile;
    }
    this.datafileManager = new datafileManager.HttpPollingDatafileManager(datafileManagerConfig);
    this.datafileManager.start();
    this.__readyPromise = this.datafileManager.onReady().then(
      this.__onDatafileManagerReadyFulfill.bind(this),
      this.__onDatafileManagerReadyReject.bind(this)
    );
    this.datafileManager.on('update', this.__onDatafileManagerUpdate.bind(this));
  } else if (this.__configObj) {
    this.__readyPromise = Promise.resolve({
      success: true,
    });
  } else {
    this.__readyPromise = Promise.resolve({
      success: false,
      reason: getErrorMessage(projectConfigCreationEx, 'Invalid datafile'),
    });
  }