var net = require('net');

const HOST = '127.0.0.1';
const PORT = 18001;
var tcpClient = new net.Socket();

tcpClient.connect(PORT,HOST,function(){
    console.log('connect success');
    tcpClient.write('this is tcp client by Node.js');
});

tcpClient.on('data',function(data){
    console.log('received: ',data.toString());
});

[root@localhost test]# node tcpClient.js

错误如下：

 events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: connect ECONNREFUSED
    at errnoException (net.js:905:11)
    at Object.afterConnect [as oncomplete] (net.js:896:19)