proxy API for node event emitters (prototype)

event-proxy.js

var EventEmitter = require('events').EventEmitter;

var request = new EventEmitter;

function Proxy(emitter, callbacks) {
  if (!(this instanceof Proxy)) return new Proxy(emitter, callbacks);
  var self = this;

  // callbacks...
  Object.keys(callbacks).forEach(function(event){
    emitter.on(event, function(){
      // but less slow
      var args = [].slice.call(arguments);

      // proxy callback
      args.push(function(err){
        // emit the error or whatever
        var args = [].slice.call(arguments, 1);
        args.unshift(event);
        self.emit.apply(self, args);
      });

      callbacks[event].apply(null, args);
    });
  });

  // pretend we wildcard error, end, and
  // others that do not define a callback
  emitter.on('end', function(){
    self.emit('end');
  });
}

Proxy.prototype.__proto__ = EventEmitter.prototype;

var req = Proxy(request, {
  data: function(data, fn){
    fn(null, data.toUpperCase());
  }
});

req.on('data', function(chunk){
  console.log(chunk.toString());
});

req.on('end', function(){
  console.log('end');
});



request.emit('data', 'foo');
request.emit('data', 'bar');
request.emit('end');

// FOO
// BAR
// end


// we could maybe add some common shortcuts,
// though I dont think they add much value

Proxy.data = function(emitter, fn){
  return Proxy(emitter, { data: fn });
};

var req = Proxy.data(req, function(data, fn){
  fn(null, data.toUpperCase());
});