Cannot send multiple UDP messages in node js - node.js

Question

I am trying to understand dgram with a small example of client/server. However, it seems that I can only send 1 message per run of the client. If I try to send multiple messages like in below client code, nothing gets sent.
Server code:
var PORT = 16501;
var HOST = '127.0.0.1';
var dgram = require('dgram');
var server = dgram.createSocket('udp4');
server.on('listening', function () {
var address = server.address();
console.log('UDP Server: ' + address.address + ":" + address.port);
});
server.on('message', function (message, remote) {
console.log('Received: ' + remote.address + ':' + remote.port +' - ' + message);
});
server.bind(PORT, HOST);
Client code:
var PORT = 16501;
var HOST = '127.0.0.1';
var dgram = require('dgram');
var client = dgram.createSocket('udp4');
var i;
for(i=0;i<10;i++) {
client.send('Test Message', 0, 12, PORT, HOST, function(err, bytes) {
if (err) throw err;
console.log('Send: ' + HOST +':'+ PORT);
});
}
client.close();
This client code works but can only send 1 message.
var PORT = 16501;
var HOST = '127.0.0.1';
var dgram = require('dgram');
var client = dgram.createSocket('udp4');
client.send('Test Message', 0, 12, PORT, HOST, function(err, bytes) {
if (err) throw err;
console.log('Send: ' + HOST +':'+ PORT);
client.close();
});
How can I make it so that it can send packets one after the other continuously?

Answer 1

You are closing the socket connection before the operations ends. I can suggest a flag to close it only after all the messages was sent, something like:
var totalReq = 10;
for (var i = 0; i < totalReq; i++) {
sendMessage(i, totalReq);
}
function sendMessage(index, total) {
client.send('Test Message', 0, 12, PORT, HOST, function(err, bytes) {
if (err) throw err;
console.log('Send: ' + HOST + ':' + PORT);
// close the connection only after the last request
if (index == total - 1) {
client.close();
}
});
}