デバッグのベストプラクティス

function NPClaims(user, context, callback) {
    /*
     * This rule (https://auth0.com/docs/rules) is used to derive
     * effective claims associated with the Normalized User Profile:
     *   https://auth0.com/docs/user-profile/normalized/auth0
     */
    var LOG_TAG = '[NORMALIZED_PROFILE_CLAIMS]: ';
    var DEBUG = configuration.DEBUG ? console.log : function () {};
    DEBUG(LOG_TAG, "identities=", user.identities);
    user.user_metadata = user.user_metadata || {};

    //
    user.family_name =
      user.family_name ||
      user.identities.filter(function(identity) {
        /* Filter out identities which do not have anything synonymous with
         * Family Name
         */
        return(
          identity.profileData &&
          identity.profileData.family_name);
      }).map(function(identity) {
        return identity.profileData.family_name;
      })[0];
    DEBUG(LOG_TAG, "Computed user.family_name as '", user.family_name, "'");
      .
      .

    //
    return callback(null, user, context);
  }