[ 原始碼： node-through ]
套件：node-through（2.3.8-1）
simplified stream construction
Easy way to create a Stream that is both readable and writable.
Pass in optional write and end methods.
through takes care of pause/resume logic if you use this.queue(data)
instead of this.emit('data', data).
Use this.pause() and this.resume() to manage flow.
Check this.paused to see current flow state.
(write always returns !this.paused).
This function is the basis for most of the synchronous streams in event-stream.
Node.js is an event-based server-side JavaScript engine.