JavaScript callbacks function object

Question

i try to learn node.js and try to create a new TCP Server connection. The code

var server = require('net').createServer(function(socket) {
  console.log('new connection');

  socket.setEncoding('utf8');

  socket.write("Hello! You can start typing. Type 'quit' to exit.\n");

  socket.on('data', function(data) {
    console.log('got:', data.toString());
    if (data.trim().toLowerCase() === 'quit') {
      socket.write('Bye bye!');
      return socket.end();
    }
    socket.write(data);
  });

  socket.on('end', function() {
    console.log('Client connection ended');
  });

}).listen(4001);

look at the callback function, after then, they call listen method. What is this for kind of object.

Could you re-state your question? It's a bit difficult to understand in its current phrasing. — ASGM
– ASGM, Commented Apr 27, 2013 at 14:24

NilsH · Accepted Answer · 2013-04-27 14:28:08Z

1

What it basically says is:

function myHandler(socket) {
   // everything up to socket.on('end')
}

var server = require('net').createServer(myHandler);
server.listen(4001);

So it's just creating a socket server with a handler function, and then make the server listen to port 4001.

answered Apr 27, 2013 at 14:28

NilsH

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1 Comment

softshipper Over a year ago

method listen() is a function from server object. I see. Thanks so much

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