Simplify callbacks using function.bind or var self = lame;

bind.js

var level = require('level');

//
// Store data from the collector to a leveldb database.
//
var DbController = function(db, collector) {
  this.db = level(db);
  this.collector = collector;
  
  //
  // The data event needs access to the `db` property, but
  //    rather than storing a reference to `this` (`var _this = this;`),
  //    the context is bound using function.bind.
  //
  this.collector.on('data', function(data) {
    this.db.put(data.name, data.value, function(err) {
      if (err) console.error(err);
    });
  }.bind(this));
};

//
// Exposes the ability to get data that was persisted from
//    the collector.
//
DbController.prototype.get = function(name, fn) {
  this.db.get(name, fn);
};


module.exports = function(db, collector) {
  return new DbController(db, collector);
};