Question

The Node.js documentation provides an example for creating an echo server:

var net = require('net');
var server = net.createServer(function (c) {
  c.write('hello\r\n');
  c.pipe(c);
});
server.listen(8124, 'localhost');

What purpose does this line serve?

  c.pipe(c);

Answer 1

c1.pipe(c2); is a short version for

c1.on('data', function(buf) { c2.write(buf); });

(plus ‘drain’ event handling, pause/resume etc – see docs)

So c.pipe(c) means ‘echo data sent to c’.