NodeJS流-泄漏的管道？

Question

I'm doing a lot of work with NodeJS streams at the moment.

One thing I find myself needing is a 'leaky pipe'.

Like stream.PassThrough , but which just drops data if (and only if) it has no where to send it.

Does such a thing already exist?

Is there a way of finding out (within a stream.Transform ) how many downstream pipes are connected?

Answer 1

I eventually came up with a solution:

LeakyTransform.prototype._transform = function(chunk, encoding, done) {
  if (this._readableState.pipesCount > 0) {
    this.push(chunk);
  }
  done();
}

Answer 2

PassThrough implements _transfrom as following:

PassThrough.prototype._transform = function(chunk, encoding, cb) {
  cb(null, chunk);
};

I think what you need can be implemented like this:

Leak.prototype._transform = function(chunk, encoding, cb) {
};

ie no-op