Node.js: muxing logger

muxing-logger.js

var es = require('event-stream');
var util = require('util');

function Logger() {
  this.stream = es.through();
  this._streamWrite = this.stream.write.bind(this.stream);
  this._streamEnd = this.stream.end.bind(this.stream);
  this.stream.write = this.stream.end = function() {};
}

Logger.prototype.log = function(msg) {
  var line = util.format('[log] %s', msg);
  this._streamWrite(line + '\n');
};

Logger.prototype.bufferedStream = function() {
  var buffered = es.split();
  var self = this;
  buffered.pipe(es.through(function(line) {
    self._streamWrite(line + '\n');
  }));
  return buffered;
};


var logger = new Logger();
logger.stream.pipe(process.stdout);
console.log('-- start --');
logger.log('1');

var evil = es.through();
evil.pipe(logger.stream); // pipe to the main stream? O NOES
evil.write('THIS SHOULD BREAK NOTHING'); evil.end();

var s1 = logger.bufferedStream();
s1.write('a');
logger.log('2');
s1.write('b');
logger.log('3');
s1.write('c'); s1.end();
logger.log('4');

var s2 = logger.bufferedStream();
var t2 = es.through(function(s) { this.queue(s.toUpperCase()); });
t2.pipe(s2);
t2.write('d');
logger.log('5');
t2.write('e');
t2.write('f'); t2.end();
logger.log('6');
console.log('-- end --');

output.txt

-- start --
[log] 1
[log] 2
[log] 3
abc
[log] 4
[log] 5
DEF
[log] 6
-- end --