是否有 NodeJS 的“直通”流？

Question

Is there a NodeJS 'passthrough' stream?

ie an object where whatever I put in to it comes out immediately, unchanged.

It seems pointless, but it would be useful as a 'static centre' for rapidly changing code during development.

Answer 1

Yeah. Actually, by that very name. :)

stream.PassThrough

It's available with Node 0.10 and later as part of the Streams 2 update (mentioned at the end).

It's also one of the few types from Streams that can be directly instantiated:

var pass = new stream.PassThrough();

And, it's currently documented briefly under API for Stream Implementors (towards the bottom of the Steams ToC ).

Answer 2

it's really handy when you need to send input bytes of a TCP Server to another TCP Server.

In my microcontroller application's web part i am using this as follows

   var net = require('net'),
       PassThroughStream = require('stream').PassThrough,
       stream = new PassThroughStream();

   net.createServer({allowHalfOpen: true}, function(socket) {
     socket.write("Hello client!");
     console.log('Connected:' + socket.remoteAddress + ':' +    socket.remotePort);
     socket.pipe(stream, {end: false});
     }).listen(8080);

   net.createServer(function(socket) {
     stream.on('data', function (d) {
      d+='';
      socket.write(Date() + ':' + ' ' + d.toUpperCase());
    });
   socket.pipe(stream);
   }).listen(8081);