Sending data from client to server in Node.js

Question

I'm trying to write a simple client-server program in Node.js where the client will enter 2 arguments (for example, user will type S 4 to get the value of the square root of 4) for a mathematical computation, send it to the server, and the server will return the answer. It works for the most part; however, when the server returns the answer, the client displays the answer and also displays the original input. Can anyone point out why this is happening?

server.js

var net = require('net');

var server= net.createServer(function(c) {
  console.log('server connected');

  c.on('end', function() {
    console.log('server disconnected');
  });

  c.on('data', function(data) {
    data = data.toString().split(" ");
    var num = parseInt(data[1], 10);
    switch (data[0]){
      case 'S':
        c.write(Math.sqrt(num).toString());
    }
  });

  c.write('What would you like to do?\n');
  c.write('(S) - Square root <arg>\n');
  c.pipe(c);
});

server.listen(3000, function() {
  console.log('server bound');
});

client.js

var net = require('net');
var num = 1;

var client = net.connect({port:3000}, function() {
    console.log('client connected');
});

client.on('data', function(data) {
  if (num == 1) {
    console.log(data.toString());

    process.stdin.resume();
    process.stdin.once('data', function(input) {
      client.write(input);
    });

    num++;
  } else {
    console.log("Server returned: " + data.toString() + "\n");
    process.exit();
  }
});

client.on('end', function() {
  console.log('\nclient disconnected\n');
});

To clarify: when I input S 4 in the client, the result printed to the screen is Server returned: 2S 4

Answer 1

You are piping the input to the output