I am developing a node.js program that connects over UDP with another program running on the same machine. Currently I am sending data like this:

import dgram = require("dgram");
const client = dgram.createSocket("udp4");

//Some code to structure the message how the server wants it
const message = Buffer.alloc(413);
message.write("TEST\0");

client.send(message, 0, message.length, 49000, '127.0.0.1', (err) => {
    if (err) {
        this.client.close();
        console.error(err);
    }
});

This works fine, however, I want to do the code in two steps. First open the connection, and then send the message. This is the code that I wrote (skipping some repeted things):

//const message same as above

this.client.bind(49000, '127.0.0.1', (err) => {
    if (err) {
        this.client.close();
        console.error(err);
    } else {
        this.client.send(message, 0, message.length, (err) => {
            if (err) {
                this.client.close();
                console.error(err);
            }
        });
    }
});

This throws the error: throw new ERR_SOCKET_BAD_PORT(name, port, allowZero); RangeError [ERR_SOCKET_BAD_PORT]: Port should be > 0 and < 65536. Received 0.

Edit:

Thanks leitning! .connect() is exactly what I needed. I now have another issue. When I do .send() directly without calling .connect() before I can receive incoming datagrams by creating a .on('message') listener on the client. But when I connect and then send, the listener doesn't receive any incoming messages. I tested this with Wireshark and there are incoming messages.

The code is:

import dgram = require("dgram");
const client = dgram.createSocket("udp4");

const message = Buffer.alloc(413);
message.write("TEST\0");

client.connect(49000,'127.0.0.1',err => {
    if (err) console.error(err);
    client.send(message, 0, message.length, 49000, '127.0.0.1', (err) => {
        if (err) {
            this.client.close();
            console.error(err);
        }
    });
});
client.on('message',(data) => {
    console.log(data);
});

Is there something I missed from the docs as to how to receive messages after doing .connect() ?