[ch0wn]

Those are not equivalent. You still have to pass on the parameters:

    this.setup = function () {
      this.on('tweet', (e, data) => this.handleStreamEvent('tweet', e, data));
      this.on('retweet', (e, data) => this.handleStreamEvent('retweet', e, data));
    };

[ianstormtaylor]

Good catch. Once they are added though, it feels a lot more readable than the "bind" alternative.