create a udp server in javascript

To create a UDP server in JavaScript, you first need to install the 'dgram' module. This module provides functionality for creating datagram sockets in Node.js, which are used for network communication via UDP.

index.tsx
const dgram = require('dgram');
const server = dgram.createSocket('udp4');

server.on('message', (msg, rinfo) => {
  console.log(`Received: ${msg} from ${rinfo.address}:${rinfo.port}`);
});

server.on('listening', () => {
  const address = server.address();
  console.log(`UDP server listening on ${address.address}:${address.port}`);
});

server.bind(1234); // bind to port 1234
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In the code above, we create a new UDP server using the dgram module and bind it to port 1234. The server.on('message') event is emitted whenever a UDP message is received, and logs the message and sender IP/port to the console.

To send a message from the client to this server, you can use the following code:

index.tsx
const dgram = require('dgram');
const message = Buffer.from('Hello, server!');
const client = dgram.createSocket('udp4');
client.send(message, 1234, 'localhost', (err) => {
  client.close();
});
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In the client code, we create a new UDP socket using dgram, and send a message to the server at localhost:1234. The client.send() method takes a Buffer object as the message parameter, and can also include the sender IP/port if needed.

Overall, creating a UDP server in JavaScript using Node.js is relatively straightforward, with the 'dgram' module providing all the necessary functionality for creating and handling UDP datagrams.