node-minecraft-protocol/examples/client_auto/client_auto.js

var mc = require('minecraft-protocol');

if(process.argv.length < 4 || process.argv.length > 6) {
  console.log("Usage : node echo.js <host> <port> [<name>] [<password>]");
  process.exit(1);
}

mc.createClientAuto({
  host: process.argv[2],
  port: parseInt(process.argv[3]),
  username: process.argv[4] ? process.argv[4] : "echo",
  password: process.argv[5]
}, function(err, client) {
  if (err) throw err;

  client.on('connect', function() {
    console.info('connected');
  });
  client.on('disconnect', function(packet) {
    console.log('disconnected: '+ packet.reason);
  });
  client.on('chat', function(packet) {
    var jsonMsg = JSON.parse(packet.message);
    if(jsonMsg.translate == 'chat.type.announcement' || jsonMsg.translate == 'chat.type.text') {
      var username = jsonMsg.with[0].text;
      var msg = jsonMsg.with[1];
      if(username === client.username) return;
      client.write('chat', {message: msg});
    }
  });
});