This is portion of the https://github.com/ibolmo/github-spy main index.js file. Refactored, and documented for edification.

github-spy-partial.js

var pagesEnroute = {};
var keensEnroute = {};
var uid = 0;

USERS.forEach(function(user){

  var handleEvents = function(err, events){

    if (err) throw new Error(err);

    debug('found ' + events.length + ' events');

    // loop from ealiest first
    events.reverse().forEach(function(activity){

      // ensure we are progressing in time
      // the db looks like an object with { username: timestamp }
      // noticed that GitHub activity events' ids are naturally ascending
      if (Number(activity.id) > Number(db[user] || 0)) {

        // update last seen timestamp
        db[user] = activity.id;
        
        var payload = {
          user: user,
          keen: { timestamp: new Date(activity.created_at).toISOString() },
          actor: activity.actor.login,
          repo: activity.repo.name
        };

        debug(user + ' (' + activity.type + ') ' + JSON.stringify(payload, null, '  '));

        var i = uid++;
        // set flag that keen is trying to post a tracking event
        keensEnroute[i] = true;

        keen.recordEvent(activity.type, payload, function(){
          // thanks to function scope we can delete the flag.. regardless of success
          delete keensEnroute[i];

          // if there are no keen tasks posting a tracking event we are done
          // this assumes that recordEvent is slower than a process tick
          if (!Object.keys(keensEnroute).length){
            debug('all events tracked');
            process.exit();
          }
        });
      }
    });

    // the response (events) is in descending order. this gets last item (earliest activity)
    var earliest = events.slice(-1)[0];
    var needsToFetchMore = earliest && (Number(earliest.id) > Number(db[user]));
    
    debug(user + (needsToFetchMore ? ' needs to fetch more' : ' has no more events'));

    if (github.hasNextPage(events) && needsToFetchMore){
      debug('Getting next page: ' + events.link);
      github.getNextPage(events, handleEvents);
    } else {
      debug('Done. Last event: ' + db[user]);
      fs.writeFileSync(DB_FILE, JSON.stringify(db, null, '  '));
      delete pagesEnroute[user];

      if (!Object.keys(pagesEnroute).length){
        debug('all pages requested');
      }
    }
  };

  
  // set flag that we're getting the events for the user via the github api
  pagesEnroute[user] = true;
  
  github.activity.getEventsForUser({ user: user, per_page: 100 }, handleEvents);
});